高回填明洞土壓力影響因素及減載措施研究
發(fā)布時間：2018-11-06 08:23
【摘要】：隨著我國西部大開發(fā)戰(zhàn)略的深入實施，西部山區(qū)的基礎(chǔ)設(shè)施建設(shè)得到了大力的發(fā)展，由于受地形起伏較大等因素的制約，高回填明洞也愈來愈廣泛的被用于鐵路、公路等大型基礎(chǔ)設(shè)施建設(shè)當中。土壓力是此類工程設(shè)計與施工中結(jié)構(gòu)所受荷載的主要來源，但目前我國各類規(guī)范中，針對高回填明洞土壓力的計算方法不多，按照《公路橋涵設(shè)計通用規(guī)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壓力影響因素及有效的土壓力計算方法，對于我國工程建設(shè)具有重要意義。 本文依托新建蘭渝鐵路蘭州樞紐工程長壽山隧道二號明洞為工程背景，先對前人研究的各種土壓力計算理論進行了解析，又通過對工程模型進行簡化與處理，借助大型通用有限元計算軟件ANSYS的強大的模擬功能，做了以下工作： （1）模擬研究了邊坡坡度、溝底與結(jié)構(gòu)的寬度比、結(jié)構(gòu)處于溝底的位置及回填土容重對高回填明洞土壓力的影響。并擬合出了以容重和回填高度為基本參數(shù)的高回填明洞的非線性土壓力計算公式。 （2）研究了拱頂鋪設(shè)EPS板、加筋橋減載和旋噴樁處理土體三種減載措施，以結(jié)構(gòu)安全系數(shù)、二次襯砌混凝土開裂和地基承載力三方面為切入點，分析三種減載措施下的結(jié)構(gòu)安全性，從而對三種減載措施的減載效果作出評價。 通過研究，得出了以下主要結(jié)論： （1）高回填明洞上方回填土壓力，與理論值相比，呈現(xiàn)出明顯的非線性關(guān)系。在回填高度小于20m時，土壓力接近于理論值；回填高度大于20m時，土壓力小于理論值，且此時回填土體存在著拱效應，隨著回填高度的增大，拱效應越來越明顯。 （2）邊坡坡度、溝底與結(jié)構(gòu)的寬度比、結(jié)構(gòu)處于溝底的位置及回填土容重都對高回填明洞土壓力有一定的影響。其中邊坡越陡，溝底與結(jié)構(gòu)寬度比越小，越有利于拱效應的形成，相同回填高度下，拱頂土壓力越小。結(jié)構(gòu)處于溝底坡腳比處于溝底中心位置所受土壓力要小。容重對土壓力的影響最大，且容重越大，越有利于土體拱效應的形成。 （3）拱頂鋪設(shè)EPS板、加筋橋減載和旋噴樁處理土體三種減載措施都能夠有效的減小明洞拱頂所受土壓力，其中旋噴樁處理土體減載效果最好，，且對于控制二次襯砌混凝土的開裂也都具有良好的效果。但對于減小仰拱下地基基礎(chǔ)所受壓力，效果不明顯。
[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.
【學位授予單位】：蘭州交通大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：U451;U455
本文編號：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.
【學位授予單位】：蘭州交通大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：U451;U455
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本文編號：2313718
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