地下鉄開削トンネルから伝播する列車走行時振動について，固体伝播音予測や振動対策検討時の基礎資料の提供を行うことを目的に，地盤内の減衰特性について検討を行った．まず，東京都内および近郊の複数地点において，開削トンネル内および地表部の振動加速度を測定し，1/3オクターブバンド分析を行った．これをもとに，振動加速度の分布状況や周波数ごとの減衰傾向を把握するとともに，シールドトンネルの例と比較した．また，Bornitzの計算式を適用した各周波数バンドごとの内部減衰定数の算出などを行い，周波数と内部減衰定数の関係を示した．これより，Bornitzの計算式を基本式として用いて，1/3オクターブバンドごとに地盤内の減衰を計算することが可能となった．

土木学会論文集C（地圏工学）, Vol. 69, No. 2, pp. 162-173, (2013)に誤りがありましたので修正しました．

The effects of earth pressure balanced (EPB) tunneling on the soil stress path and piezometric head of the soil during tunnel advancement are considered in this study. First, the 3D stress distributions of the area near the crown and spring line of the tunnel are investigated, after which the tunnel stress path with respect to the Mohr-Coulomb yielding surface is presented. Next, by taking into account the three significant factors of a) advance rate of the tunnel face, b) consolidation coefficient of the soil, and c) overburden depth of the tunnel, a parametric study is conducted and the effect of EPB tunneling on the piezometric head field of the soil is examined.

軟弱な粘性土地盤中に建設されたシールドトンネルでは，周辺地盤の圧密によって変形が緩慢ながらも長期的に進行する場合がある．これを予測するには土水連成解析が有効な手法であるが，変形の進行を精度良く予測するためには，ひび割れによる覆工剛性の非線形性を考慮することが必要である．しかし，土水連成解析で広域的に地盤をモデル化して変形挙動を求める際に，材料のひび割れによる精緻な非線形挙動を考慮することは計算コストの面などから現実的ではない．そこで本研究では，室内実験と実計測結果との比較から，ひび割れ発生による影響を簡易なリング一様の剛性低下で表現する手法を考案し，その妥当性を確認した．

軟弱な粘性土地盤中に建設されたシールドトンネルでは，周辺地盤の圧密によって変形が緩慢ながらも長期的に進行する場合がある．これを予測するには土水連成解析が有効な手法であるが，変形の進行を精度良く予測するためには，ひび割れによる覆工剛性の非線形性を考慮することが必要である．しかし，土水連成解析で広域的に地盤をモデル化して変形挙動を求める際に，材料のひび割れによる精緻な非線形挙動を考慮することは計算コストの面などから現実的ではない．そこで本研究では，室内実験と実計測結果との比較から，ひび割れ発生による影響を簡易なリング一様の剛性低下で表現する手法を考案し，その妥当性を確認した．

近年，薬液注入工法については数多くの研究開発が進められ，液状化対策のように長期的な改良効果を期待する工事にも利用されている．しかし一方で，設計の観点からは，長期経過後の薬液注入工法による改良体の物理的な状態変化を定量的に予測する手法がないことが課題となっていた．そこで本研究では，実験室で促進養生した改良体の物性値変化を把握し，この物性値変化に薬液に含まれるシリカが密接に関係していることを解明した．この促進養生に伴う改良体内部のシリカ濃度変化を表現できる拡散方程式に基づく数値解析手法を構築し，その妥当性を促進養生試験結果をもとに確認した．さらに，この手法を利用して実地盤における薬液注入による改良体の100年後の物理的な状態を推定し，改良体の耐久性評価の考え方を提案した．

The chemical grouting has the advantages that equipments are small and the direction of boring has flexibility. Therefore, in Japan, it is frequently used for a soil-improvement method in the railway construction site where workspace or working hours is limited. However, it has the possibility to cause a ground displacement around the site. Because there is no method that estimates it quantitatively, the design based on old cases is still used mainly and focuses on safety overly.
In this Study, the simplified numerical analysis for ground behavior due to the osmotic pressure during injection is proposed.

軟弱な粘性土地盤中に建設されたシールドトンネルには，長期的な圧密作用で内空変位やひび割れ・継手目開きが生じる場合があることが知られている．しかし，多岐の要因で生じるひび割れ・継手目開きから，圧密に起因するものを特定することは困難であることから，トンネルが経験した環境履歴に応じたひび割れ・継手目開きの進展過程を再現する計算法が必要である．そこで本研究では，実トンネルのシミュレーションを通して，このようなひび割れ・継手目開きを再現できる数値解析法を提案する．

水素は将来の環境に良いクリーンエネルギーとして，実用化に大きな期待が寄せられている．この 1つの活用形態として，埋設導管による水素ガスの燃料電池への供給構想が国内外で検討されている．これらを実現する上で，最も重要となるのが保安確保である．これには配管材料の信頼性評価だけでなく，万一の水素ガス漏出時の地中での移動範囲や速度などの移動特性に関する知見が極めて重要で，安全な設備の設計や維持管理を行う上で基盤となる．これら水素ガス供給用埋設導管の保安確保の基礎を確立するため，実大規模の水素ガスの地中漏出実験と数値解析を実施して地中における水素ガスの移動特性を確認するとともに，水素ガスの漏洩検知技術の確立を目的として各種の埋設場所・条件下での水素ガスの移動特性を調査した．

水素は将来の環境に良いクリーンエネルギーとして，実用化に大きな期待が寄せられている．この 1つの活用形態として，埋設導管による水素ガスの燃料電池への供給構想が国内外で検討されている．これらを実現する上で，最も重要となるのが保安確保である．これには配管材料の信頼性評価だけでなく，万一の水素ガス漏出時の地中での移動範囲や速度などの移動特性に関する知見が極めて重要で，安全な設備の設計や維持管理を行う上で基盤となる．これら水素ガス供給用埋設導管の保安確保の基礎を確立するため，実大規模の水素ガスの地中漏出実験と数値解析を実施して地中における水素ガスの移動特性を確認するとともに，水素ガスの漏洩検知技術の確立を目的として各種の埋設場所・条件下での水素ガスの移動特性を調査した．

Chemical grouting method is employed frequently within on urban area to improve the strength and permeability characteristics of soft ground. In order to ensure the long term performance of chemically stabilized sand with grouting, the systematic field measurement of the mechanical characteristics of the chemical grouted sandy soil has been carried out by the Japanese Grouting Association for the period of five years, from 2000 to 2005. The test field soil condition consisted mainly of comparatively dense sand with gravel and the ground water table was around 6 m below the ground surface. Four types of silicate grouting materials were employed. Standard penetration tests (SPT), lateral loading tests (LLT), in-situ permeability tests and flow meter tests within a bored hole were conducted to obtain the strength and permeability characteristics of the grouted sand. The SPT-N value and LLT deformation modulus of the grouted sand with a silicate material of an organic hardener has increased for the initial two years and then decreased for the next year. However, its N-value was still the triple times the initial one. It has been concluded that silicate grouted materials have demonstrated the satisfactory performance during the period of three years.

During road excavations for laying gas distribution pipelines, the reuse of the excavated soil for the subgrade backfill significantly reduces the environmental impact. However, when Kanto loam soil, which is a local soil that is widely distributed in the Kanto region, Japan, is employed for the backfill material, the relationship between the amount of the subsidence of the subgrade soil and the cyclic traffic loading must be investigated. In this study, cyclic loading tests on compacted Kanto loam soils are conducted to investigate the subsidence characteristics by using a confined compression apparatus. The subsidence prediction method for subgrade soil (Kanto loam soil) under cyclic traffic loading is proposed on the basis of the cyclic loading test results. Full-scale traffic loading experiments are performed on roadbeds backfilled with Kanto loam soil. Consequently, good correlation is obtained between the amount of the predicted subsidence and the measurement results.

Soil washing is physical-chemical separation for removing the portion of the soil that is most polluted mainly by screen, hydrocyclone, and flotation. This reduces the amount of soil needing further cleanup. In most cases, the contaminants, such as fuels and heavy metals, reside and concentrated in fine-grained soils. The overflow from the hydrocyclone, consisting of fines and water, is treated and converted to a 45%-55% dry solids sludge cake by flocculants addition, sedimentation, thickening, and dewatering. This sludge cake contains the target contaminants and therefore must be managed by disposal at a properly permitted off-site disposal facility. The fines treatment is very important for the recovery of water and for making the sludge cake as dry as possible, in order to create an economical and efficient soil washing system. The proper selection of type and dosage of flocculants is crucial to the success of the fine treatment. This paper describes and proposes a new theory to determine the optimum dosage of flocculants (polymers) based on the soil plasticity index and the pH value. This theory concerning the optimum dosage was verified by subsequent data in the soil washing plant.

This paper focuses on a large settlement behaviour of a shield tunnel, which is constructed in soft alluvial clay strata beneath fresh reclaimed land. The total settlement of the tunnel is more than 0.73 metres and the deformation takes place over more than twenty years after the completion of the tunnel construction. Three dimensional finite element analyses have been carried out to estimate a long-term behaviour of soil and tunnel structure observed in this field. The computed vertical settlement of tunnel structure is compared with the measured data.

A novel stabilizing liquid using air foam rather than bentonite clay slurry, i.e. air foam suspension, is employed in order to stabilize the trench wall surface during a diaphragm wall excavation. Air foam suspension is used to reduce the construction costs of working on an underground diaphragm wall. Air foam suspension is created by mixing the excavated soil with air foam made from a surface-active chemical agent. The performance of air foam suspension depends on its density and consistency, that is, its table flow value (TF). By comparing the trench stabilization capacity of air foam suspension with that of bentonite clay slurry in model tests, the appropriate performance of air foam suspension was confirmed. The cost evaluation of using an air foam suspension for a diaphragm wall excavation is presented.

A novel stabilizing liquid using air foam rather than bentonite clay slurry, i.e. air foam suspension, is employed in order to stabilize the trench wall surface during a diaphragm wall excavation. Air foam suspension is used to reduce the construction costs of working on an underground diaphragm wall. Air foam suspension is created by mixing the excavated soil with air foam made from a surface-active chemical agent. The performance of air foam suspension depends on its density and consistency, that is, its table flow value (TF). By comparing the trench stabilization capacity of air foam suspension with that of bentonite clay slurry in model tests, the appropriate performance of air foam suspension was confirmed. The cost evaluation of using an air foam suspension for a diaphragm wall excavation is presented.

A novel stabilizing liquid using air foam rather than bentonite clay slurry, i.e. air foam suspension, is employed in order to stabilize the trench wall surface during a diaphragm wall excavation. Air foam suspension is used to reduce the construction costs of working on an underground diaphragm wall. Air foam suspension is created by mixing the excavated soil with air foam made from a surface-active chemical agent. The performance of air foam suspension depends on its density and consistency, that is, its table flow value (TF). By comparing the trench stabilization capacity of air foam suspension with that of bentonite clay slurry in model tests, the appropriate performance of air foam suspension was confirmed. The cost evaluation of using an air foam suspension for a diaphragm wall excavation is presented.

The Japanese National Committee for TC28 has produced a committee report on current underground construction activities in Japan, including the technologies of braced excavation and tunneling.
This report is based on technical papers and available construction records from the past decade. In the field of braced excavation, the topics of proximity construction, excavation machines for braced walls, deep shaft excavation, and groundwater flow preservation measures have been selected and introduced, along with some case records. In the field of tunneling, statistical data on tunneling in Japan has been assembled from published data and questionnaires. Several case records using current shield tunneling and urban NATM methods are described. Finally, damages to underground structures due to the 1995 Hyogoken-Nanbu (Kobe) Earthquake are summarized, and new earthquake-resistant designs for shield tunneling and other technologies are introduced.

The Japanese National Committee for TC28 has produced a committee report on current underground construction activities in Japan, including the technologies of braced excavation and tunneling. This report is based on technical papers and available construction records from the past decade. In the field of braced excavation, the topics of proximity construction, excavation machines for braced walls, deep shaft excavation, and groundwater flow preservation measures have been selected and introduced, along with some case records. In the field of tunneling, statistical data on tunneling in Japan has been assembled from published data and questionnaires. Several case records using current shield tunneling and urban NATM methods are described. Finally, damages to underground structures due to the 1995 Hyogoken-Nanbu (Kobe) Earthquake are summarized, and new earthquake-resistant designs for shield tunneling and other technologies are introduced.

The effectiveness of grouting to reduce surface settlements during underground construction in clayey ground was investigated by a field trial and laboratory tests. The field trial was carried out during shield tunnelling work conducted in alluvial clay deposits in Koto-ku, Tokyo. Grout was injected at some distance away from the tunnel, and both surface and subsurface settlements above the tunnel were monitored. Although the initial heave was achieved immediately after the grout injection, the ground continued to settle with time, owing to soil consolidation and grout shrinkage. A laboratory investigation was conducted to investigate the parameters that control the long-term behaviour of grouting in clay. It was found that better long-term grout efficiency can be achieved in overconsolidated clay than in normally consolidated clay, and the efficiency increased with increasing injection volume. Finite element analysis of the laboratory experiments confirmed that the amount and extent of excess pore pressures generated during injection govern the longterm grout efficiency. Finite element analysis of the field trial was also performed to simulate the long-term ground deformation after grout injection.

The effectiveness of grouting to reduce surface settlements during underground construction in clayey ground was investigated by a field trial and laboratory tests. The field trial was carried out during shield tunnelling work conducted in alluvial clay deposits in Koto-ku, Tokyo. Grout was injected at some distance away from the tunnel, and both surface and subsurface settlements above the tunnel were monitored. Although the initial heave was achieved immediately after the grout injection, the ground continued to settle with time, owing to soil consolidation and grout shrinkage. A laboratory investigation was conducted to investigate the parameters that control the long-term behaviour of grouting in clay. It was found that better long-term grout efficiency can be achieved in overconsolidated clay than in normally consolidated clay, and the efficiency increased with increasing injection volume. Finite element analysis of the laboratory experiments confirmed that the amount and extent of excess pore pressures generated during injection govern the longterm grout efficiency. Finite element analysis of the field trial was also performed to simulate the long-term ground deformation after grout injection.

The aim of this study is to develop a laboratory ground movement measuring device and apply it to a model test of shield tunneling. The thin flexible metal plate was used for measuring ground displacement, to which the strain gauges were affixed. The calibrations of soil displacement obtained from this measuring device were carried out by the trap door tests. The potential of the laboratory ground movement measuring device was demonstrated for the use to measure the ground displacement during shield driving. Furthermore, a series of model tests were carried out to investigate the ground displacement behaviour during shield machine driving.

During shield tunnelling operation, a shield machine is driven forward by applying mechanical jack forces behind the machine tail and excavating the soil in front of the machine with its cutting face. In this study, the advancement and excavation processes of the shield tunnelling operation are modelled using the finite element method in order to investigate the effect of these construction processes on the ground response. A new excavating finite element, which models the disturbed soil in front of the cutting face, is introduced. The operation of shield advancement and of soil excavation is simulated using the finite element remeshing technique at each time step of the analysis. The accuracy of the finite element remeshing technique is discussed by analysing one-dimensional consolidation of an isotropic elastic medium. The proposed modelling techniques of shield tunnelling construction are applied to simulate a tunnelling project in Tokyo and the numerical results are compared with the field measurements. The soil deformation mechanism associated with the shield tunnelling operation is examined in detail.

During shield tunnelling operation, a shield machine is driven forward by applying mechanical jack forces behind the machine tail and excavating the soil in front of the machine with its cutting face. In this study, the advancement and excavation processes of the shield tunnelling operation are modelled using the finite element method in order to investigate the effect of these construction processes on the ground response. A new excavating finite element, which models the disturbed soil in front of the cutting face, is introduced. The operation of shield advancement and of soil excavation is simulated using the finite element remeshing technique at each time step of the analysis. The accuracy of the finite element remeshing technique is discussed by analysing one-dimensional consolidation of an isotropic elastic medium. The proposed modelling techniques of shield tunnelling construction are applied to simulate a tunnelling project in Tokyo and the numerical results are compared with the field measurements. The soil deformation mechanism associated with the shield tunnelling operation is examined in detail.

In closed water environments such as lakes or marshes, soil and organic materials deposit at the bottom. In order to solve problems of land smells or water pollution, bottom deposits have been dredged or stabilized with cement. Recently, the reuse of lake-bottom deposits for agricultural compost has been planned, but an efficient flocculation and dewatering method for high water content lake deposits is necessary for this to be implemented. In this study, a series of sedimentation experiments and consolidation tests on lake-bottom deposits dredged from a closed water environment lake were carried out using an organic flocculant. It is shown from the experimental results that an optimum volume of flocculant does exist for efficient sedimentation and that the addition of flocculant improves the dewatering characteristics of lake-bottom deposits.

This paper introduces a numerical simulation procedure for use with the shield tunnelling problems and compares the simulation results with field measurements for soft clay ground. The shield machine advance is simulated numerically by adopting excavation elements and repetitively rearranging the three-dimensional finite element mesh used in the simulation. Deformation of soft clay ground and the effective stress behaviour as the shield machine advances under actual hydraulic jacking forces are modelled successfully by the new procedure. As an example, the application of this procedure to the twin shield tunnelling problem is described.

This paper introduces a numerical simulation procedure for use with the shield tunnelling problems and compares the simulation results with field measurements for soft clay ground. The shield machine advance is simulated numerically by adopting excavation elements and repetitively rearranging the three-dimensional finite element mesh used in the simulation. Deformation of soft clay ground and the effective stress behaviour as the shield machine advances under actual hydraulic jacking forces are modelled successfully by the new procedure. As an example, the application of this procedure to the twin shield tunnelling problem is described.

Drained torsion shear tests of anisotropically consolidated undisturbed clay were carried out using hollow cylindrical specimens, in order to investigate the effects of principal axes rotation particularly on the dilatancy characteristics of undisturbed clay. The magnitude of dilatancy is considered to represent the microstructural change of undisturbed clay during the drained torsion shear process. The plastic volumetric strain of clay was experimentally observed to occur just due to the principal axes rotation under constant mean principal stress p' and principal stress difference q drained shear conditions. The plastic Volumetric strain increment of undisturbed clay under a magnitude of principal axes rotation was found to be greater than that of reconstituted clay.

This paper introduces a numerical simulation procedure for use with the shield tunnelling problems and compares the simulation results with field measurements for soft clay ground. Shield machine advance is simulated numerically by adopting excavation elements and repetitively rearranging the three-dimensional finite element mesh used in the simulation. Deformation of soft clay ground and the pore water pressure behaviour as the shield machine advances under actual hydraulic jacking forces are modelled successfully by the new procedure. As an example; the application of this procedure to tile twin shield tunnelling problem is described.

Soil-cement mixtures were prepared using three types of materials sandy soil excavated from a shield tunnelling construction site in Tokyo, clay slurry used for stabilizing the shield tunnel cutting face, and cement. These soil-cement mixtures were planned to be used for the filling of the lower part (invert section) of the circular shield tunnel cross-section in place of cement mortar. A number of unconfined compression tests were carried out to investigate the time-dependent variation of compressive strength of soil-cement mixtures. The strength of soil-cement mixture was found to be satisfactory as the new invert material and to be influenced by the contents of the clay slurry. It could be seen that the density of soil-cement mixtures measured immediately after mixing and compaction was directly related to the compressive strength.