深挖方溢洪道黄土地基承载力取值问题研究
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摘要
深挖方溢洪道土质地基承载力的选取关系到边墙支挡结构的设计和溢洪道底板的配筋设计,对于溢洪道设计至关重要。本文结合陕西某水库溢洪道消力池的黄土地基工程,分析了几个规范的不同点认为:对于溢洪道边墙这样的支挡结构和底板,由于其受力机理不同于建筑物的整体失稳,不应该进行板宽和挖深校正;同时由于土体的卸荷再加荷模量较加荷模量大得多,而载荷试验由于载荷板尺寸较小,测定的地基承载力只能反映地基土卸荷膨胀区域的值,较实际承载力小。建议对于挖深大于5m的土质地基,在载荷试验测定地基土承载力后,应该比较该值与原上覆土体自重应力,若前者小于后者应该按照后者取值。
The selection of soil foundation bearing capacity for deep excavated spillway is very important for spillway design,because it is related to the design of side wall supporting and retaining structure and spillway floor reinforcement. This paper analyzed the difference in the codes by combining the loess foundation engineering of stilling basin of a reservoir spillway in Shaanxi. The suggestion is that it doesn't need to correct width plate and excavated deep for side wall supporting and retaining structure and spillway floor,because they have different stress mechanism with building 's overall instability. Meanwhile,because the loading after unloading modulus of soil is much higher than the loading modulus and the size of load board is small in loading test,the foundation bearing capacity by loading test only reflects the value of expansive area after unloading and is lower than practical bearing capacity. So it is suggested that foundation bearing capacity by loading test should be compared with gravity stress of original overlying soil for foundation excavation depth more than 5m. The foundation bearing capacity should adopt the value of gravity stress of original overlying soil when foundation bearing capacity by loading tests is lower.
The selection of soil foundation bearing capacity for deep excavated spillway is very important for spillway design,because it is related to the design of side wall supporting and retaining structure and spillway floor reinforcement. This paper analyzed the difference in the codes by combining the loess foundation engineering of stilling basin of a reservoir spillway in Shaanxi. The suggestion is that it doesn't need to correct width plate and excavated deep for side wall supporting and retaining structure and spillway floor,because they have different stress mechanism with building 's overall instability. Meanwhile,because the loading after unloading modulus of soil is much higher than the loading modulus and the size of load board is small in loading test,the foundation bearing capacity by loading test only reflects the value of expansive area after unloading and is lower than practical bearing capacity. So it is suggested that foundation bearing capacity by loading test should be compared with gravity stress of original overlying soil for foundation excavation depth more than 5m. The foundation bearing capacity should adopt the value of gravity stress of original overlying soil when foundation bearing capacity by loading tests is lower.
引文
[1]张爱军,谢定义.复合地基三维数值分析[M].北京:科学出版社,2004.
[2]肖大平,朱维一,陈环.滑移线法求解极限承载力问题的一些进展[J].岩土工程学报,1998,(4):25-29.
[3]SMITH C C.Complete limiting stress solutions for the bearing capacity of strip footings on a Mohr-Coulomb soil[J].Géotechnique,2005,55(8):607-612.
[4]赵同顺,周波.大型油罐地基变形特性的研究[J].岩石力学与工程学报,2004,23(6):1037-1043.
[5]张爱军,任文渊,谢定义.散体桩复合地基承载力可调节型设计方法研究[J].岩土工程学报,2010,32(9):1422-1428.
[6]陈保国,骆瑞萍,徐颖.软土地基上高填方刚性涵洞地基承载力分析[J].岩土力学,2013,34(2):353-358.
[7]李胜伟,王铁行,苏立君.条形荷载下黄土地基沉降基础尺寸效应分析[J].地下空间与工程学报,2010,6(3):636-639+649.
[8]陈保国,董佳竹.软土地基上高填方刚性涵洞地基处理及其设计原则[J].土木工程与管理学报,2012,29(3):11-16.
[2]肖大平,朱维一,陈环.滑移线法求解极限承载力问题的一些进展[J].岩土工程学报,1998,(4):25-29.
[3]SMITH C C.Complete limiting stress solutions for the bearing capacity of strip footings on a Mohr-Coulomb soil[J].Géotechnique,2005,55(8):607-612.
[4]赵同顺,周波.大型油罐地基变形特性的研究[J].岩石力学与工程学报,2004,23(6):1037-1043.
[5]张爱军,任文渊,谢定义.散体桩复合地基承载力可调节型设计方法研究[J].岩土工程学报,2010,32(9):1422-1428.
[6]陈保国,骆瑞萍,徐颖.软土地基上高填方刚性涵洞地基承载力分析[J].岩土力学,2013,34(2):353-358.
[7]李胜伟,王铁行,苏立君.条形荷载下黄土地基沉降基础尺寸效应分析[J].地下空间与工程学报,2010,6(3):636-639+649.
[8]陈保国,董佳竹.软土地基上高填方刚性涵洞地基处理及其设计原则[J].土木工程与管理学报,2012,29(3):11-16.