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地下气库的围岩稳定性关系到地下气库的安全与使用。影响地下洞室稳定的因素很多,解析法虽然可以得到精确解,但是只能针对圆形洞室。而数值计算方法可以计算各种情况下围岩的应力、变形、塑性分布等情况。利用有限元分析软件分析了洞室形状对围岩稳定性的影响,确定了合理的洞形;讨论了围岩应力应变随深度的变化规律,以及不同的支护类型对围岩变形的影响,确定了经济合理的支护类型。最终为该地质条件下的洞室围岩稳定设计提供了依据。 相似文献
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Jiang Kaihui Yao Minglun Lecturer Tianjin University Tianjin Professor Tianjin University Tianjin 《中国海洋工程》1994,(1)
-This paper presents the research results of dynamic pore water pressure and the characteristics of dynamic deformation of saturated soft clay and the factors affecting the dynamic pore water pressure and dynamic deformation. Dynamic triaxial compression tests are carried out and the soil samples used in the tests are remoulded clay from the seabed of the Bohai Bay. The paper also deals with the dynamic deformation mechanism of saturated soft clay foundation without drain. A calculation model for permanent dynamic deformation of saturated soft clay foundation has been established. 相似文献
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目前在防波堤设计和施工中,较少考虑软粘土的蠕变特性对软土地基长期变形的影响.为准确预测斜坡堤软土地基的变形水平,研究采用Plaxis二维有限元程序,利用不考虑蠕变的摩尔-库仑模型和能反映土体时间效应的软土蠕变模型,模拟某斜坡堤地基软土层施工期和工后的地基变形过程,对比分析了两种不同模型的计算结果,表明由软土蠕变模型得到... 相似文献
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The sand compaction pile (SCP) method can be applied to soft marine clay ground that is a reinforcement of composite ground consisting of compacted sand piles and surrounding clay. The application of SCP method in the immersed tunnel of Hong Kong–Zhuhai–Macao Bridge verify SCP method is a robust solution to limit the total settlement and differential longitudinal settlement and to promote smooth transition from immersed tunnel to artificial island. The SCP method has significant settlement reduction effect on marine clay. The SCPs can also function as a drainage path to accelerate the consolidation process in marine clay. It is also found that the consolidation rate of SCP-improved ground is delayed compared with that predicted program which is most probably because of the soil disturbance effect during the installation of SCPs. 相似文献
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Cheng-Lin Zhang 《Marine Georesources & Geotechnology》2017,35(7):1018-1027
When a subway train moves through a tunnel, vibrations are generated and transmitted to soils around the tunnel and adjacent structures. Subway train operation has an impact on the shield tunnel lining and the soils around tunnel, especially soft soils that are mostly marine sediments having poor engineering properties. An elastoplastic dynamic finite difference model was built by considering the hysteretic behavior of these marine soft soils and the interaction between the soils and the tunnel to study their dynamic response. Elastic and plastic constitutive models were adopted for tunnel lining and soft soils, respectively. Hysteretic damping was obtained with the Hardin–Drnevich model to reflect the hysteretic behavior of soil under the dynamic load. There are two peaks of the cumulative vertical displacement within 2?s of train moving and it reaches a dynamic balance after 2?s. The soil layers below the shield tunnel are under the compression and the soil layers above the tunnel are in the extrusion state, and turn to uplift. Maximum bending moment and shear forces of lining vary and appear at different places. A parametric study indicates that the speed of train and the interface have an impact on the dynamic behavior of soft soils. 相似文献
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海上风电工程主要受到风、波浪及洋流等产生的水平循环荷载作用,本文研究楔形单桩基础在水平循环荷载作用下的变形规律,并探讨不同循环荷载对变形规律产生的影响,以确保风电设施正常运行。通过数值模拟建立海上风电单桩-海床模型,考虑土体超孔隙水压力的演变规律及土体致密规律,土体采用UBC3D-PLM本构模型。本文重点讨论并分析在不同水平循环荷载作用下楔形单桩基础与等截面单桩基础的桩周土体位移、塑性应变及桩基累计转角位移之间的差异。研究结果表明：楔形结构会降低桩周土体位移及塑性应变,使得楔形单桩基础旋转中心位置更低,产生倾覆的可能更小,当循环荷载比为0.7时,累计转角位移能减少41.86%;循环荷载越大,楔形单桩基础水平受荷特性越好,累计位移减少量的增长率越高。研究成果可为今后海上风电基础的选择与设计提供参考。 相似文献
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As the offshore wind turbine foundation, the four-bucket jacket foundation has a large stiffness and the structure is difficult to be damaged under seismic load. Nevertheless, the saturated subsoil of the four-bucket jacket foundation tends to be liquefied under earthquake, which greatly affects the safety of offshore wind turbine. Therefore, the seismic performance of four-bucket jacket foundation is mainly reflected in the anti-liquefaction capacity of foundation soil. In this paper, the liquefaction resistance of sandy soil of four-bucket jacket foundation for offshore wind turbine is studied. The liquefaction and dynamic response of sandy soil foundation of four-bucket jacket foundation under seismic load are obtained by carrying out the shaking table test, and the influence mechanism of four-bucket jacket foundation on the liquefaction resistance of sandy soil foundation is analyzed.
相似文献10.
Shu-Guang Song Shu-Cai Li Li-Ping Li Qian-Qing Zhang Kai Wang Yi Zhou 《Marine Georesources & Geotechnology》2016,34(4):376-383
During tunnel excavation, the deformation of surrounding rock due to the unloading of rock mass will vary with time. However, the measured displacement of surrounding rock is only a part of the actual longitudinal deformation profile. There is a need to analyze the longitudinal deformation profile to identify the deformation state and evaluate the stability of surrounding rock mass. In the present article, the variation of pre-deformation of surrounding rock due to excavation was analyzed, and the release coefficient was obtained from the measured results. For the Qingdao subsea tunnel, the measured crown settlement of surrounding rock was analyzed using the regression analysis method, and the longitudinal deformation profile of rock mass was simulated using the numerical calculation method. Moreover, based on the conditions of the subsea tunnel, a solid-fluid coupling model test was carried out to check the reliability of the numerical calculation results. The results of the model test were consistent with the numerical calculation results. 相似文献
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大直径单桩基础是海上风电应用广泛的一种基础形式,严格控制桩基泥面处的位移是保证基础稳定和风机安全运营的关键因素.通过数值方法建立了单桩—海床的三维模型,将可以描述海洋砂土超固结性和结构性的弹塑性本构模型通过UMAT子程序嵌入有限元软件ABAQUS中,桩基承受的波浪荷载通过Morison方程进行计算模拟.针对无波浪荷载、仅作用于海床的波浪荷载、同时作用于桩基和海床的波浪荷载三种情况,分析了海床土的动力响应以及桩基的水平位移之间的差异,探讨了海床土体参数对桩基水平变形的影响.研究结果表明海床土体液化会导致桩基水平变形增加,海床土渗透性、超固结性、结构性对桩基水平位移影响显著,研究成果可为海上风电单桩基础的设计与运维提供参考. 相似文献
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以上海复兴东路大型越江盾构隧道为工程背景。通过建立适合工程结构及工程地质特点的弹性地基模型,在充分考虑隧道结构荷载作用特点、地下水的影响及隧道下部土体反力特性的基础上,推导出了隧道纵向位移的解析表达式,并采用基于土体反力系数的迭代解析方法,计算了部分南线隧道各管片纵向位移值,所得结果与实测结果基本吻合。 相似文献
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Suction caisson foundations are often subjected to vertical uplift loads, but there are still no wide and spread engineering specifications on design and calculation method for uplift bearing capacity of suction caisson foundation.So it is important to establish an uplift failure criterion. In order to study the uplift bearing mechanism and failure mode of suction caisson foundation, a series of model tests were carried out considering the effects of aspect ratio,soil permeability and loading mode. Test results indicate that the residual negative pressure at the top of caisson is beneficial to enhance uplift bearing capacity. The smaller the permeability coefficient is, the higher the residual negative pressure will be. And the residual negative pressure is approximately equal to the water head that causes seepage in the caisson. When the load reaches the ultimate bearing capacity, both the top and bottom negative pressures are smaller than Su and both the top and bottom reverse bearing capacity factors are smaller than 1.0 in soft clay. Combined the uplift bearing characteristics of caisson in sandy soil and soft clay, the bearing capacity composition and the calculation method are proposed. It can provide a reference for the engineering design of suction caisson foundation under vertical load. 相似文献
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C. J. Garrison 《Applied Ocean Research》1989,11(4):194-201
It is common practice to compute wave-induced loads on the immersed surface of gravity structures exposed to the wave motion and disregard the pore-water pressure variation on the foundation surface. However, when the soil is porous, wave-induced pressures propagate within the soil under the structure and result in a rather significant contribution to overall loads. This paper describes a practical method for numerical modeling of the pore pressure under a gravity platform foundation for compressible water and a rigid, but porous soil. The porous soil may be bounded by an impermeable horizontal layer at some arbitrary depth.
The paper outlines the basic boundary element procedure for pore pressure analysis and presents numerical results for a typical gravity structure as well as results for comparison with an existing analytical solution for a vertical circular cylinder. 相似文献
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More and more deep-seated long submarine tunnels are under construction, which greatly promotes the development of tunneling technology. The complex geological conditions and frequent geological disasters have become great challenges during submarine tunnel excavation. Among them, casualties and economic losses caused by water inrush are on the top levels in all kinds of tunnel geological disasters. Escape routes after water inrush from the working face during submarine tunnel excavation are investigated and optimized in the present study. Numerical simulations are performed using the FLUENT software to probe water flow characteristics after inrush. Two common cases of water inrush during double-line submarine tunnel excavation are researched. The variation rules of velocity and pressure in the tunnels after inrush are analyzed and discussed. The optimized escape routes are achieved. Finally, the water movement laws after inrush from the working face under different excavation situations are further discussed by comparing the two case studies. Water inrush of high velocity occurs on one working face of the double-line submarine tunnel, and the research results are as follows: (1) The velocity close to the tunnel side wall is the minimum, while it is the maximum in the middle position. (2) The pressure changes greatly at the intersection area of the cross passage and the tunnels. (3) The velocity and pressure nearby the working face without water inrush are both small. (4) The velocity at the high location of the cross passage is relatively small. 相似文献
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The presence of a fractured zone at a tunnel face can threaten the stability of the tunnel by causing water leakage and degradation of the soil strength. In this case, to stabilize the tunnel face, the pore water pressure is generally reduced and the loss of soil particles is prevented by installing drainpipes. The installation of drainpipes, however, can cause the concentration of flow channels and other ground instability problems. In this paper, a novel pin-holed pipe anchor is proposed to overcome the problems occurring in subsea tunnels. The pin-holed pipe anchor is a pipe-type support member designed to reinforce the ground while simultaneously enabling flow into the tunnel. Here, the design requirements of the pin-holed pipe anchor were examined through material tests, and the structural–hydraulic characteristics of the pin-holed pipe anchor were investigated through a model test. Furthermore, the applicability of the pin-holed pipe anchor to an actual tunnel was evaluated by numerical analysis of actual tunnels. Through selection of an appropriate perforated drainage area and bonded length, the pin-holed pipe anchor contributed to the improvement of the structural and hydraulic stabilities of the tunnel. 相似文献
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承受水平荷载作用的桩基，规范中常采用m法进行桩基水平承载力的计算，地基土水平地基抗力系数的比例系数m值在规范中根据地基土的状态、类别以表格给出。在地基勘察中，现在广泛采用静力触探试验。直接利用静力触探数据给出比例系数m值。将使桩基设计所用参数更加直接准确。本文利用天津地区地层大量静力触探资料与地基土状态数据，利用统计分析回归方法，总结出地基土的液性指数IL与静力触探参数锥尖阻力qc及摩阻比Rf间的关系式，针对天津的地层土体，给出利用静力触探资料查用m值的表格，为桩基的设计计算提供资料。 相似文献
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为了研究海底防沉板—桩复合基础在地震荷载作用下的动力反应特性,以我国南海深水工程实例为研究对象,利用Flac3D有限差分仿真软件建立了计算模型,土体采用Mohr-Coulomb本构模型,模型底部输入EL Centro地震波,对不同桩长的复合基础进行分析计算.在该特定工程背景下,研究结果表明:随着桩长的增加,防沉板顶部加速度放大系数呈减小趋势;地震荷载下,复合基础发生震陷,沉降量在地震波加速度峰值过后趋于稳定;当桩长为6m时,复合基础的水平振动程度和震陷量最小;由于桩基础把震动能量传输到深部土层中,复合基础周围土体的加速度响应值小于远场土体.在动力时域内,防沉板与桩连接处弯矩最大,需要在此处增设加固装置. 相似文献
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Santosh Kumar Yadav Guan-lin Ye Usama Khalid 《Marine Georesources & Geotechnology》2020,38(4):400-416
AbstractBased on a new elasto-plastic constitutive model, this paper presents a soil–water coupled numerical prediction of the bearing capacity for shallow foundation constructed on Ballina soft clay for unconsolidated undrained (UU) and consolidated undrained (CU) conditions. This elasto-plastic constitutive Shanghai model has an advantage of describing the mechanical behaviour of over-consolidated and structured soil under different loading and drainage conditions, by using one set of material parameter. In this paper, the Shanghai model used for both UU and CU conditions has the same initial parameters obtained from laboratory test results. The loading conditions and consolidation stages vary based on construction details. The predicted bearing pressure-settlement responses for UU and CU, approves the field observation. The phenomenon of gaining the bearing capacity due to consolidation is captured and explained by the use of soil–water coupled numerical analysis with a new elasto-plastic model. The stress strain behaviour, stress paths and the decay of the structure of elements at different depths presented in this study, reveal the mechanism for the difference between UU and CU conditions to understand the foundation behaviour. Effect of the initial degree of soil structure on the bearing capacity is also addressed. Overall, this approach provides the integrated solution for the shallow foundation design problems under short and long-term loadings. 相似文献