检索结果-南通市图书馆

Influence of cutterhead opening ratio on soil arching effect and face stability during tunnelling through non-uniform soils

在线全文

学校读者我要写书评

暂无评论

Underground Space 2024年第4期17卷 45-59页

作者： Xue-Jian Chen Pei-Pei Fang Qiu-Nan Chen Jun Hu Kai Yao Yong Liu State Key Laboratory of Water Resources Engineering and Management Wuhan UniversityWuhan 430072China Hubei Technology Innovation Center for Smart Hydropower Wuhan 430000China College of Civil Engineering Anhui Jianzhu UniversityHefei 230601China School of Civil Engineering Hunan University of Science and TechnologyXiangtan 411201China School of Civil and Architectural Engineering Hainan UniversityHaikou 570228China School of Qilu Transportation Shandong UniversityJinan 250002China

Tunnelling has increasingly become an essential tool in the exploration of underground space.A typical construction problem is the face instability during tunnelling,posing a great threat to associated *** face instability often occurs with the soil arching *** study investigates the combined effect of cutterhead opening ratio and soil non-uniformity on soil arching effect and face stability,via conducting random finite-element analysis coupled with Monte–Carlo *** results underscore that the face stability is strongly associated with the evolution of stress *** obtained stability factors in the uniform soils can serve as a reference for the design of support pressure in practical tunnelling *** addition,non-uniform soils exhibit a lower stability factor than uniform soils,which implies that the latter likely yields an underestimated probability of face *** tunnel face is found to have a probability of failure more than 50%if the spatial non-uniformity of soil is *** the end,a practical framework is established to determine factor of safety(FOS)corresponding to different levels of probability of face failure considering various opening ratios in non-uniform *** required FOS is 1.70 to limit the probability of face instability no more than 0.1%.Our findings can facilitate the prediction of probability of instability in the conventionally deterministic design of face pressure.

关键词： Tunnel face stability Soil arching effect Cutterhead opening ratio Non-uniform soil Random field

Two-dimensional face stability analysis in rock masses governed by the Hoek-Brown strength criterion with a new multi-horn mechanism

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Mining Science and Technology 2023年第8期33卷 963-976页

作者： Junhao Zhong Xiaoli Yang School of Civil Engineering Central South UniversityChangsha 410075China

The face stability problem is a major concern for tunnels excavated in rock masses governed by the Hoek-Brown strength *** provide an accurate prediction for the theoretical solution of the critical face pressure,this study adopts the piecewise linear method(PLM)to account for the nonlinearity of the strength envelope and proposes a new multi-horn rotational mechanism based on the Hoek-Brown strength criterion and the associative flow *** analytical solution of critical support pressure is derived from the energy-work balance equation in the framework of the plastic limit theorem;it is formulated as a multivariable nonlinear optimization problem relying on 2m dependent variables(m is the number of segments).Meanwhile,two classic linearized measures,the generalized tangential technique(GTT)and equivalent Mohr-Coulomb parameters method(EMM),are incorporated into the analysis for ***,the parametric study indicates a significant improvement in support pressure by up to 13%compared with the GTT,and as expected,the stability of the tunnel face is greatly influenced by the rock strength *** stress distribution on the rupture surface is calculated to gain an intuitive understanding of the failure at the limit *** the limit analysis is incapable of calculating the true stress distribution in rock masses,a rough approximation of the stress vector on the rupture surface is *** the end,sets of normalized face pressure are provided in the form of charts for a quick assessment of face stability in rock masses.

关键词： face stability Piecewise linear method Hoek-Brown strength criterion Multi-horn rotational mechanism Limit analysis

Experimental investigation of face instability for tunnels in sandy cobble strata

在线全文

学校读者我要写书评

暂无评论

Underground Space 2023年第3期10卷 199-216页

作者： Qiguang Di Pengfei Li Mingju Zhang Xiaopu Cui Key Laboratory of Urban Security and Disaster Engineering Ministry of EducationBeijing University of TechnologyBeijing 100124China

In order to investigate the influence of face instability for tunnels with different burial depths in sandy cobble strata on earth pressure and the instability region,geomechanical model tests and numerical simulations were *** continuous excavation method was adopted to reduce the pressure of the soil bin and restore the real engineering *** pressure in three directions of the obser-vation section in front of the tunnel face was monitored during the tunneling of the *** of the lateral stress ratios at dif-ferent stages were also *** instability area of the shield tunnel face in sandy cobble strata with different burial depth ratios during the instability stage was obtained based on the change ratio of earth pressure and compared with existing *** earth pressure began to change when the excavation was one shield diameter away from the observation section,and when the excavation reached the observation section,the earth pressure decreased *** burial depth of shield tunnel in the sandy cobble strata has a significant impact on the evolution of soil arch and the size of the failure *** numerical simulation of the continuum medium cannot reflect the stress redistribution characteristics of the granular body like sandy cobble strata,and the failure area or stress distur-bance area obtained by the model test is larger than the numerical simulation *** methods have deviations in analyzing the failure area of shield tunnel face in sandy cobble *** provides not only guidance for shield tunnel excavation engineering in sandy cobble strata,but also a reference for the theoretical research on failure areas.

关键词： Geomechanical model test Sandy cobble strata face stability Arching effect Shield tunnel

Construction strategies for a NATM tunnel in Sao Paulo, Brazil, in residual soil

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Underground Space 2022年第1期7卷 1-18页

作者： Osvaldo P.M.Vitali Tarcisio B.Celestino Antonio Bobet Lyles School of Civil Engineering Purdue UniversityWest LafayetteIN 47907USA Sao Carlos School of Engineering University of Sao PauloSao CarlosSP 13566Brazil

Due to the fast growth of urban areas worldwide,the demand for tunnels in developed areas is *** design and construc-tion of those tunnels are complex because of their shallow depths and their interaction with existing aboveground and buried structures,which results in rather limited allowable ground deformations induced by the tunnel excavation and *** tropical regions,residual porous soils near the surface are *** soils are highly deformable;thus,tunneling may induce large ground deformations that may damage nearby *** new Austrian tunneling method(NATM)and the sprayed concrete lining(SCL)technique are being widely employed in several big cities in tropical regions,but little research has been conducted to assess the induced ground deformations in residual soils,common in tropical *** paper provides insight into this issue.A well-documented metro tunnel in Sa˜o Paulo,Brazil,in a residual red porous clay,was analyzed using 3D finite element method(FEM).The behavior of the residual red porous clay was approximated by an advanced constitutive soil model calibrated with triaxial tests on intact samples extracted at the *** of the tunnel deformations during construction matched the field *** calibrated model was then used to explore the tunnel per-formance under different construction *** influence of partial face excavation,unsupported span length,support stiffness and pipe roof umbrella were *** numerical results showed that partial face excavation was effective to reduce ground deformations ahead of the face of the tunnel and to improve face stability;however,the settlements behind the face increased because of the delay in closing the primary *** installation of a stiffer liner closer to the face reduced the ground deformations *** pipe roof umbrella was the most effective technique to reduce the ground deformations around the tunnel;however,the numerical results

关键词： Tunnel NATM Residual soil FEM 3D face effects Ground deformation face stability

Hard rock tunnel boring machine penetration test as an indicator of chipping process efficiency

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2017年第4期9卷 611-622页

作者： M.C. Villeneuve Department of Geological Sciences University of Canterbury Christchurch 8140 New Zealand

The transition from grinding to chipping can be observed in tunnel boring machine(TBM) penetration test data by plotting the penetration rate(distance/revolution) against the net cutter thrust(force per cutter) over the full range of penetration rates in the *** penetration test data to the geological and geomechanical characteristics of rock masses through which a penetration test is conducted provides the ability to reveal the efficiency of the chipping process in response to changing geological *** test data can also be used to identify stress-induced tunnel face *** research shows that the strength of the rock is an important parameter for controlling how much net cutter thrust is required to transition from grinding to *** also shows that the geological characteristics of a rock will determine how efficient chipping occurs once it has *** particular,geological characteristics that lead to efficient fracture propagation,such as fabric and mica contents,will lead to efficient *** findings will enable a better correlation between TBM performance and geological conditions for use in TBM design,as a basis for contractual payments where penetration rate dominates the excavation cycle and in further academic investigations into the TBM excavation process.

关键词： Penetration rate Grinding Chipping Geological characteristics face stability

Horizontal trap-door investigation on face failure zone of shield tunneling in sands

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2021年第3期28卷 866-881页

作者： LIU Xue-yan FANG Hong-yuan WANG Fu-ming YUAN Da-jun Department of Civil Engineering Beijing Forestry UniversityBeijing 100083China School of Water Conservancy and Environment Zhengzhou UniversityZhengzhou 450001China Tunnel and Underground Engineering Research Center of Ministry of Education Beijing Jiaotong UniversityBeijing 100044China

A novel horizontal trap-door test system was devised in this study to analyze the face stability of shield tunnels in *** test system can be used to investigate both the longitudinal and cross sections of the face failure simultaneously at one single apparatus and was employed to perform face stability tests on small-scaled tunnel models at single *** lateral support pressures and failure zones were studied with varying sand materials and earth *** results demonstrate that the tunnel face moves back,the lateral active earth pressure on the tunnel face decreases rapidly to a residual value,and the lateral pressure distribution can be categorized into three stages during the failure process:1)initial state;2)pressure dissipation stage;and 3)pressure zone diminution ***,face failure firstly develops from a stable condition to the local failure state,and then continues to develop to the global failure state that can be divided into two sub-zones with different failure mechanisms:rotational failure zone(lower zone)and gravitational failure zone(upper zone).Further discussion shows that under the effects of soil arching,the shape of the gravitational failure zone can adopt arch shaped(most frequent)and column shaped(in shallow tunnels).Limit support pressure for face stability usually appears atδ/D=0.2%−0.5%(ratio of face displacement to tunnel diameter).

关键词： face stability trap-door test lateral earth pressure failure zone soil arching sand