高回填明洞土压力影响因素及减载措施研究
发布时间：2018-11-06 08:23
【摘要】：随着我国西部大开发战略的深入实施，西部山区的基础设施建设得到了大力的发展，由于受地形起伏较大等因素的制约，高回填明洞也愈来愈广泛的被用于铁路、公路等大型基础设施建设当中。土压力是此类工程设计与施工中结构所受荷载的主要来源，但目前我国各类规范中，针对高回填明洞土压力的计算方法不多，按照《公路桥涵设计通用规范》中“土柱法” z H，造成了工程成本的大量增加。因此，找出高回填明洞的土压力影响因素及有效的土压力计算方法，对于我国工程建设具有重要意义。 本文依托新建兰渝铁路兰州枢纽工程长寿山隧道二号明洞为工程背景，先对前人研究的各种土压力计算理论进行了解析，又通过对工程模型进行简化与处理，借助大型通用有限元计算软件ANSYS的强大的模拟功能，做了以下工作： （1）模拟研究了边坡坡度、沟底与结构的宽度比、结构处于沟底的位置及回填土容重对高回填明洞土压力的影响。并拟合出了以容重和回填高度为基本参数的高回填明洞的非线性土压力计算公式。 （2）研究了拱顶铺设EPS板、加筋桥减载和旋喷桩处理土体三种减载措施，以结构安全系数、二次衬砌混凝土开裂和地基承载力三方面为切入点，分析三种减载措施下的结构安全性，从而对三种减载措施的减载效果作出评价。 通过研究，得出了以下主要结论： （1）高回填明洞上方回填土压力，与理论值相比，呈现出明显的非线性关系。在回填高度小于20m时，土压力接近于理论值；回填高度大于20m时，土压力小于理论值，且此时回填土体存在着拱效应，随着回填高度的增大，拱效应越来越明显。 （2）边坡坡度、沟底与结构的宽度比、结构处于沟底的位置及回填土容重都对高回填明洞土压力有一定的影响。其中边坡越陡，沟底与结构宽度比越小，越有利于拱效应的形成，相同回填高度下，拱顶土压力越小。结构处于沟底坡脚比处于沟底中心位置所受土压力要小。容重对土压力的影响最大，且容重越大，越有利于土体拱效应的形成。 （3）拱顶铺设EPS板、加筋桥减载和旋喷桩处理土体三种减载措施都能够有效的减小明洞拱顶所受土压力，其中旋喷桩处理土体减载效果最好，，且对于控制二次衬砌混凝土的开裂也都具有良好的效果。但对于减小仰拱下地基基础所受压力，效果不明显。
[Abstract]:With the further implementation of the strategy of developing the western regions of China, the infrastructure construction in the western mountainous areas has been greatly developed. Due to the constraints of the large terrain fluctuation and other factors, the high-backfill Ming Cave has been more and more widely used in the railway. Highway and other large-scale infrastructure construction. The earth pressure is the main source of the load on the structure in the design and construction of this kind of engineering, but there are few calculation methods for the earth pressure of the high backfill open hole in all kinds of codes of our country at present. According to the general code for highway bridge and culvert design, the "soil column method" z H has resulted in a large increase in engineering cost. Therefore, it is of great significance to find out the influencing factors of earth pressure and the effective calculation method of earth pressure for high backfill open hole. Based on the engineering background of Changshoushan Tunnel No. 2 in Lanzhou Hub Project of Lanzhou-Chongqing Railway, this paper first analyzes various earth pressure calculation theories studied by predecessors, and then simplifies and deals with the engineering model. With the help of the powerful simulation function of ANSYS, the following works are done: (1) the slope, the ratio of the bottom to the width of the structure, are simulated and studied. The influence of the structure at the bottom of the gully and the bulk density of the backfill on the earth pressure of the high backfill tunnel. The nonlinear earth pressure calculation formula of the high backfill tunnel with bulk density and backfill height as the basic parameter is fitted. (2) three kinds of load reduction measures, such as EPS plate laid on arch roof, load reduction of reinforced bridge and treatment of soil by rotary jet pile, are studied. The breakthrough points are structural safety factor, cracking of secondary lining concrete and bearing capacity of foundation. The structural safety of the three load reduction measures is analyzed, and the load reduction effect of the three load reduction measures is evaluated. The main conclusions are as follows: (1) the backfill earth pressure above the high backfill tunnel shows obvious nonlinear relationship compared with the theoretical value. When the backfill height is less than 20m, the earth pressure is close to the theoretical value, and when the backfill height is higher than 20m, the earth pressure is less than the theoretical value, and there is an arch effect in the backfill soil. With the increase of backfill height, the arch effect becomes more and more obvious. (2) Slope slope, width ratio of bottom to structure, position of structure at bottom and bulk density of backfill have certain influence on soil pressure of high backfill tunnel. The steeper the slope and the smaller the ratio of the bottom to the width of the structure, the more conducive to the formation of the arch effect. At the same backfill height, the earth pressure of the arch roof is smaller. The earth pressure of the structure at the foot of the slope is smaller than that at the center of the bottom. The effect of bulk density on soil pressure is the greatest, and the larger the bulk density is, the more favorable is the formation of soil arch effect. (3) with the EPS plate laid on the arch roof, the load reduction measures of reinforced bridge and rotary jet pile can effectively reduce the earth pressure on the arch roof of the open hole, among which the load reduction effect of rotary jet grouting pile is the best. It also has good effect on controlling the cracking of secondary lining concrete. However, the effect is not obvious for reducing the pressure on the foundation under the inverted arch.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U451;U455
本文编号：2313718
[Abstract]:With the further implementation of the strategy of developing the western regions of China, the infrastructure construction in the western mountainous areas has been greatly developed. Due to the constraints of the large terrain fluctuation and other factors, the high-backfill Ming Cave has been more and more widely used in the railway. Highway and other large-scale infrastructure construction. The earth pressure is the main source of the load on the structure in the design and construction of this kind of engineering, but there are few calculation methods for the earth pressure of the high backfill open hole in all kinds of codes of our country at present. According to the general code for highway bridge and culvert design, the "soil column method" z H has resulted in a large increase in engineering cost. Therefore, it is of great significance to find out the influencing factors of earth pressure and the effective calculation method of earth pressure for high backfill open hole. Based on the engineering background of Changshoushan Tunnel No. 2 in Lanzhou Hub Project of Lanzhou-Chongqing Railway, this paper first analyzes various earth pressure calculation theories studied by predecessors, and then simplifies and deals with the engineering model. With the help of the powerful simulation function of ANSYS, the following works are done: (1) the slope, the ratio of the bottom to the width of the structure, are simulated and studied. The influence of the structure at the bottom of the gully and the bulk density of the backfill on the earth pressure of the high backfill tunnel. The nonlinear earth pressure calculation formula of the high backfill tunnel with bulk density and backfill height as the basic parameter is fitted. (2) three kinds of load reduction measures, such as EPS plate laid on arch roof, load reduction of reinforced bridge and treatment of soil by rotary jet pile, are studied. The breakthrough points are structural safety factor, cracking of secondary lining concrete and bearing capacity of foundation. The structural safety of the three load reduction measures is analyzed, and the load reduction effect of the three load reduction measures is evaluated. The main conclusions are as follows: (1) the backfill earth pressure above the high backfill tunnel shows obvious nonlinear relationship compared with the theoretical value. When the backfill height is less than 20m, the earth pressure is close to the theoretical value, and when the backfill height is higher than 20m, the earth pressure is less than the theoretical value, and there is an arch effect in the backfill soil. With the increase of backfill height, the arch effect becomes more and more obvious. (2) Slope slope, width ratio of bottom to structure, position of structure at bottom and bulk density of backfill have certain influence on soil pressure of high backfill tunnel. The steeper the slope and the smaller the ratio of the bottom to the width of the structure, the more conducive to the formation of the arch effect. At the same backfill height, the earth pressure of the arch roof is smaller. The earth pressure of the structure at the foot of the slope is smaller than that at the center of the bottom. The effect of bulk density on soil pressure is the greatest, and the larger the bulk density is, the more favorable is the formation of soil arch effect. (3) with the EPS plate laid on the arch roof, the load reduction measures of reinforced bridge and rotary jet pile can effectively reduce the earth pressure on the arch roof of the open hole, among which the load reduction effect of rotary jet grouting pile is the best. It also has good effect on controlling the cracking of secondary lining concrete. However, the effect is not obvious for reducing the pressure on the foundation under the inverted arch.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U451;U455
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