共查询到20条相似文献，搜索用时 15 毫秒
1.
According to the characteristics of interfacial stress between surrounding rock and shotcrete support, mechanical model of composite curved beame for support system of tunnel surrounding rock and shotcrete lining was established, considering the interfacial deformation coordination and the effects of bearing arch of surrounding rock. Then from static equilibrium of two differential elements, the differential equations for the radial displacement of composite curved beam were obtained. All analytic formulas of both interfacial stress and internal forces between surrounding rock and shotcrete lining by arbitrary distribution load were derived. And thus the mechanical condition of interface zone and the stress concentration position were obtained, which is convenient to assess the stability of surrounding rock and predict the safety. Finally, the analysis of tunnel project excavated by bench method showed that shotcrete lining made the formation of compressive stress zone in surrounding rock by transferring stress from the interface between surrounding rock and shotcrete, which is beneficial to improve the stability of surrounding rock. 相似文献
2.
Recently, the construction of neighboring highway tunnels with small interval gets more and more in China. The construction of such tunnels proceeds usually by excavating one after another. The second tunnel is constructed with the surrounding rock disturbed by the first one. And the construction of second tunnel also has effect on the first excavated one. For revealing the interaction laws of such tunnel construction in combination with the engineering practice of Lanfeng tunnel at Jinshan Road in Chongqing, The FE numerical simulation analysis was used to study the characters of surrounding rock deformation, stress field, and plastic zone of the tunnel. From this analysis, it clearly shows that the excavation of second tunnel has significant influence on the first one. This study provides a scientific basis for design and excavation of neighboring highway tunnels. 相似文献
3.
According to the measurement during excavation of Jinzhou tunnel with four lanes in one cave which lies on the rebuilt highway from Shenyang to Dalian, this paper analyzes the rock deformation rule, discusses the reason of instability after a highway tunnel was excavated, emphasizes the necessity of the construction stability monitor and active control. The importance of support is Fresented with bolts and shotcrete to improve and enhance the carrying capability of the rock. It is necessary to insist on the rule of measurement and active control to ensure the safety and quality of tunnel construction. 相似文献
4.
Elasto-plastic analysis on surrounding rock of roadways based on seepage, strain softening and dilatancy 总被引：1，自引：0，他引：1
According to seepage body force, strain softening and rupture expansion of rock mass, elastic-plastic mechanics theory, distribution laws of stress and displacement of surrounding rock in seepage field are derived, and relationships between different zonation range of the surrounding rocks, pore water pressure, strain softening and rupture expansion are established. The results show that the pore water pressure and rupture expansion rock mass have a more obvious impact on the surrounding rock rupture area than the plastic zone. Both the plastic zone and the rupture area are larger when the seepage field is considered. The impact of strain softening on both the plastic zone and the rupture zone of surrounding rock is very significant, and both seepage and strain softening rupture expansion affect deformation of surrounding rock of roadways obviously. It provides certain reference values for the roadway support engineering in seepage field. 相似文献
5.
According to the strain nonlinear softening constitutive model having inflexion point after peak stress of practical rock and considering intermediate principal stress, the plastic zone of circular cavern with liner under the condition of uniform pressure is analyzed. The elasto - plastic boundaries both for the lining and surrounding rock are discussed. The stress distribution law is different due to the different position of elastic - plastic boundary. Based on this, different stress formulas are gained. The critical pressure caused by excavation of cavern leading to the yield zone and that caused by inner pressure leading to the yield of the liner and surrounding rock is introduced. 相似文献
6.
Elastic-Perfectly Plastic Solution of Tunnel Surrounding Rocks Using Mogi-Coulomb Strength Criterion
Lyu Caizhong 《保鲜与加工》2014,(6):54-59
Reasonable choice of rock strength criteria is crucial for stress and displacement prediction and support design in tunnel engineering. Based on Mogi-Coulomb strength criterion and elastic-perfectly plastic model, analytical solutions of stress and displacement for surrounding rocks around a circular tunnel were derived The intermediate principal stress coefficient was used to present the intermediate principal stress effect. The results in this study were compared with the current solutions in the literatures and the influence of intermediate principal stress and shear strength parameters of surrounding rocks was discussed. The results showed extensive applicability and the Mohr-Coulomb strength criterion and Matsuoka-Nakai criterion are two special cases; when the intermediate principal stress coefficient b was equals to 0.5, the results indicated that the intermediate principal stress effect and its range for rock strength; the influence of cohesion and internal friction angle on the plastic radius and tunnel wall displacement was significant; Care should be taken to the effects of intermediate principal stress and shear strength parameter variations of surrounding rocks on tunnel design and construction. 相似文献
7.
When tunnels are through water bearing section of fractured rock mass, a complex interaction process between rock mass deformation and fluid transportation is one of the most important reasons for water gushing, water bursting and mud bursting.To study the rock mass deformation and fluid transportation in tunnel excavation under complex geological conditions, a hydraulic model of complex crack rock mass was established from the relationship between the crack growth degree of surrounding rock in deep buried tunnel and the engineering scale, with which fracture network of different levels in rock mass could be considered simultaneously.Furthermore,a computer Fortran program was put forward to simulate the solid fluid coupling of excavation process of a deep buried tunnel.And it was found that the principal fractures had strong flowing action and network fractures had storage function and lag effect in seepage area.And the yield area of surrounding rock was increased under the coupling of seepage field and stress field. 相似文献
8.
This paper uses the Mohr-Coulomb criterion with tension cut-off strain-softening model and the large-strain calculation method to study the localized deformation and progressive failure.It investigates the process of stain localization appearing,growing and sample failure,and uses the physical and numerical simulation to explore the relationship between strain localization and progressive failure of surrounding rock.The results show that the soften character of rock sample is caused by stain localization.The breach point of progressive failure is founded based on the distribution law of plastic zones and soften strips.The key causes of the tunnel convergence deformation after opening are the plastic extrusion and the elastic deformation of rock yield units caused by stress release. 相似文献
9.
Tunnel portal section mostly faces unfavorable geologic and topographical conditions, such as broken surrounding rock, shallow and unsymmetrical loadings. The current Chinese code for design of road tunnel provides the load calculation method of tunnel under unsymmetrical. However, according to the mechanic and deformation characteristics of the tunnel lining on site, the assumption is not suitable for the shallow tunnel under unsymmetrical loadings in broken surrounding rock. Therefore, through engineering case analysis and results of three-dimensional numerical analysis, the failure mechanism of shallow tunnel under unsymmetrical loadings in broken surrounding rock is presented firstly, that is, deep buried side broken surrounding rocks slump down after excavation and squeeze the lining, which makes the lining deform outward and bear passive earth pressure. Through the failure mechanism, the surrounding rock mainly includes slumping area and passive area. Then the corresponding formulas are deduced based on limit equilibrium theory. Finally, a case study is adopted to verify the feasibility of the new method. It is show that the new method is more reasonable than the method of current code. 相似文献
10.
Based on dynamic time history analysis, dynamic response behavior of an un supported tunnel through fault zone which was simulated by interface and solid elements was studied under uniform input earthquake wave excitation. The analyses of response behaviors, including displacement difference, acceleration magnification, and plastic zones and so on, were carried out when earthquake wave excitation was input along transverse, longitudinal and vertical of tunnel respectively. The results show that simulation method for fault zone is effective; the earthquake causes obvious displacement difference at fault zone and surrounding rock contacting part. The maximal displacement difference reaches to 51.8mm under transverse uniform input earthquake wave excitation. And the displacement difference under vertical and longitudinal is only 44.3% and 23.1% of the transverse value, respectively; the acceleration magnification in fault zone is significantly greater than that in surrounding rock. Shear failure zone appears at the fault zone and surrounding rock contacting part, and it is especially prominent under input longitudinal earthquake wave excitation. It is proposed that fault zone has significantly influence on the dynamic performance of tunnel. The fault zone and the transitional zones are the control zones of seismic design when tunnel passes through fault zone, thus, the study on the anti seismic measures should be further strengthened. 相似文献
11.
Creep characters of tunnel supports structure is analyzed according to triaxial creep test of concrete specimen of deep tunnel supports structure adopting MTS815 hydraulic servo system. The creep parameters of nonlinear creep model are presented based oncreep curve. The finite element numerical model has been established considering tunnel construction process, creep characters of surrounding rock and support structure. The displacement characteristics, the effective stress and the maximum shear stress in different position in primary support and second lining are obtained through creep characters analysis of surrounding rock and supports structure. The features of displacement and stress dependent time of tunnel supports has visible difference comparing with discard creep effect and calculation displacement and practical monitoring results is basic concordance. The creep characters of surrounding rock and tunnel supports should be considered for deep tunnel. 相似文献
12.
以重庆东水门大桥—千厮门大桥渝中区连接隧道为研究对象,基于UDEC软件建立离散元数值模拟分析模型,研究了城区连拱隧道施工引起的地表沉降,上部建筑物基础沉降及倾斜,新建隧道下方已有轨道六号线的变形、受力特征,并将监测数据与数值模拟进行对比分析。结果表明,连拱隧道左侧隧道上导坑施工引起的隧道拱顶沉降和基础沉降量最大,经计算上部建筑物基础最大沉降量为3.81 mm,最大倾斜量为0.02%,建筑物基础沉降量和倾斜在规范许可范围之内;隧道施工引起的地层损失使得轨道六号线左拱肩向上隆起,六号线弯矩分布规律和其变形形态基本一致,弯矩最大值位于左拱肩部位,最大值为238 kN·m;数值模拟计算结果与监测数据量值相当,变形趋势基本一致;采用UDEC软件可以准确地计算出隧道开挖过程中节理的存在对隧道周围建筑物变形的影响。 相似文献
13.
14.
Calculation of Influence on Longitudinal Deformation of Adjacent Tunnels Due to Excavation 总被引：1，自引：0，他引：1
Unloading of excavation of foundation pit has influence on adjacent tunnels, therefore it is important to predict the deformation of metro tunnels to ensure the operation of tunnel. The displacement effect due to the surrounding wall soil unloading of adjacent excavation was not considered by the theoretical analysis method, and the analysis procedure of FEM was usually too complicated to get a satisfied result, so the horizontal and vertical additional stress were calculated by the Mindlin solutions. Furthermore, the tunnel structure was considered as the beam with infinite length. The additional stress was imposed on the Winkler model and the governing equation was built up on the adjacent tunnel structure. Finally, displacements and internal forces of existing tunnels were obtained. Compared with the numerical simulation and an engineering case, the results of the presented formula are in good agreement. It can provide certain theoretical and calculation basis for metro tunnels influenced by adjacent excavation. 相似文献
15.
Excavation of an intersection tunnel between independent double tunnels leads again to stress release and redistribution in the surrounding rock and the support structure of the chief tunnel, resulting in change of mechanical behavior of the rock mass an 相似文献
16.
Rock is a kind of physical nonlinear complicated medium, under deep buried condition the surrounding rock system deformation shows geometrical nonlinear characteristic, and the interaction between the two nonlinear mechanism makes the unloading of surrounding rock system evolving complexly. Based on the Lagrangian method and large deformation caculation method, both the double nonlinearity and nonlinear dynamics character of deep buried tunnel surrounding rock system under unloading are studied. The numerical model results show that the Kolmogorov entropy has been extracted from the evolution data in the unloading process of surrounding rock system. The analysis indicates that the typical chaos character has been demonstrated in the process of unloading for deep buried tunnel surrounding system and the rock mass energy dissipation is analyzed at the stage of unloading. 相似文献
17.
In the Wenchuan earthquake, steep dip bedding slope is a kind of slope that seismic mountain disaster very development and the slope earthquake disaster is often exacerbated by the excavation. In order to reproduce the process and analysis regularity of slope deformation and failure under the action of seismic load. The author chooses San Shuping landslide located Pingwu County as the typical examples of steep dip excavation damage bedding slope, and the indoor physical model test of slope deformation and failure under the action of seismic load are carried out. The results show that slope deformation and failure is intensified by the excavation. Collapse and sliding is the main form of failure and the results consistent with the field investigation. From the whole process of deformation and failure of view, it can be divided into the four stages. First, the initial phase of the earthquake. A wedge rock by excavation small slides along the rock layers and the slope toe stress increase sharply under the action of seismic load in this stage. Second, rock layers by excavation break-bend at slope toe. Third, the rock layers by excavation overall decline stage. Last, the rock slide blocked and dumping. 相似文献
18.
DAI Gao-fei~ 《保鲜与加工》2004,(2):132-135166
It is important that monitor measuring is applied in tunnel in regard to NATM. The monitor measuring of NATM was studied in the Fengmeiya Tunnel in Chongzun Express. Based on the regularity and conditions of the surrounding rock deformation of monitor measuring in site, the optimum time for primary and permanent support are obtained which averting successfully accidents in construction, enhancing the construction qualities and guidance to tunnel construction in Karst areas. 相似文献
19.
Elastic-Plastic Analysis of Surrounding Rocks Considering Material Dilatancy and Softening 总被引：2，自引：0，他引：2
Wei Jianjun 《保鲜与加工》2013,(3):7-11
Based on stress dropping model, an elastoplastic-brittle model was established by using a softening threshold value to model the features of the geotechnical materials. According to the Mohr-Coulomb criterion, the radius of the rupture and plastic zone, the displacement and stress expressions of surrounding rock were obtained with the consideration of the strain-softening and dilatancy of geotechnical materials. Furthermore, the model was verified by case study and the influence of strain-softening, dilatancy and elastic modulus deterioration on calculation result were presented. 相似文献
20.
According to the characteristics of plane strain problem of elastic and plastic mechanics, the bi parametric expressions were derived for stress components satisfying the generalized Hoek Brown failure criterion. Being substituted into the static equilibrium partial differential equations, a group of first order hyperbolic pseudo linear differential equation partial differential equations was obtained. Utilizing the determinant method and proper variable transformation, the characteristic direction and the differential relation equation for the stress partial differential equations were acquired. The characteristic direction indicted that in plastic zone obliquely intersecting conjugate shear slip surfaces formed two families of non orthogonal slip lines, in which conjugate angle varied with the limit stress state and the material physical properties of Hoek Brown rock mass. Since the principal direction of the maximum principal stress was circumferential in perfectly elasto plastic surrounding rock of the plastic zone around a circular opening suffering the symmetric initial stress field, the angle between the tangential direction of slip line with the principal direction of the maximum principal stress was the function of the minimum principal stress(i.e. the radial stress). Combined with the analytical solution, the polar coordinate differential equation was derived and furthermore, the polar coordinate curve equation for the slip line was obtained. 相似文献