【作者】 周应华；

【导师】 周德培；

【作者基本信息】 西南交通大学 ， 岩土工程， 2006， 博士

【摘要】 本文以南渝、安楚高速公路的典型红层路堑边坡的研究对象,在广泛的地质资料调研和工程地质特性分析的基础上,采用理论研究、数值分析和大型地质力学模型试验,对红层路堑边坡变形破坏机理、稳定性分析及加固防护措施进行了深入系统的研究。同时利用大量岩样的室内试验和现场试验,研究了红层岩体力学参数的选取原则。通过理论分析和试验研究,得出的主要结论和研究成果如下: (1)根据红层路堑边坡的工程地质特征,按坡体结构将边坡分为近水平、倾斜和上覆堆积层三大类。按岩性组合和结构体特征又将近水平边坡细分为软质泥岩为主的岩体结构、砂泥岩互层的软硬相间的岩体结构、巨厚层砂岩为主的岩体结构,不同岩性组合的近水平边坡破坏机理共有8种;根据岩层倾向和边坡倾向的关系将倾斜边坡岩体结构进一步划分为为顺层、反倾和斜交边坡三个亚类,其中的顺层边坡破坏机制主要为完全平面顺层—滑移型、滑移—拉裂型和滑移—弯曲型三种,反倾边坡的失稳过程分为弯曲—倾倒—滑移三个阶段,斜交红层边坡的破坏形式可分为阶梯状顺层滑塌、阶梯状顺节理滑塌和楔形滑塌三种。 (2)提出了红层岩体力学参数选取原则。①通过对试验结果和收集的资料分析,对红层岩石、结构面的力学性质、水理及风化特性有了较为完整的认识;②系统阐述了利用H-B公式计算节理岩体力学参数,研究了BQ指标与RMR指标之间的关系,总结出了利用BQ指标估算岩体弹性模量的经验公式。③结合红层边坡坡体结构和红层的特殊力学性质,提出了红层岩体力学参数的选取方法。边坡岩体所含结构面在4组以下者,主要根据不同地区岩块和结构面力学参数试验值的随机模糊统计结果来选取;而边坡岩体中结构面组数在4组以上者,则应用Hoek-Brown经验强度准则来确定整个节理岩体的综合力学参数。 (3)近水平红层路堑边坡稳定性研究。用数值方法对近水平红层中砂泥岩软硬互层边坡开挖变形机理进行分析;对拉裂崩塌破坏采用岩石的抗拉强度对其稳定性进行评价;对后缘陡倾节理发育的平推式滑坡的稳定性评价方法进行了研究,得出了当节理里面充满水时,裂缝位于坡项线的位置时边坡具有最小的稳定性系数的结论。 (4)倾斜红层路堑边坡稳定性研究。建议先用赤平投影图对倾斜红层边更多还原

【Abstract】 Based on extensive geological investigation and analysis, deformation and failure mechanism, stability analysis and support measures of road cut slope in red beds are studied systematically and thoroughly in this paper. The author uses theoretic, numerical analysis and large-scale model tests to assist his research. Methods oriented by the typical projects of the red bed road cut slopes involved in the highway from Nanchong to Chongqing and the highway from Anning to Chuxiong in Yunnan Province. The mechanic parameters of rock mass in red bed are simultaneously studied by using large numbers of laboratory test and field test. The main results of this paper can be summed up as follows:1. On the basis of geologic engineering investigation, the formation structure of red bed slope is classified as dip slope, accumulative formation slope and approximate horizontal slope, which is classified as three types in slope structure: mudstone, interbedded strata of sandstone and mudstone, heavy sandstone. According to lithological combination characters, approximately horizontal slope has eight failure modes. Considering the relationship between the dip of bedding plane and the dip of slope, the dip red bed slope is further divided into three subgroups: consequent bedding rock slope, countertendency bedding slope and oblique crossing bedding slope. First, the deformation and failure mode consists of three types among consequent bedding rock slope: bedding sliding, sliding and fracturing, bending and fracturing. Secondly, the deformation and failure modes of coutertendency bedding slope are bending, toppling and sliding. Finally the failure modes of oblique crossing bedding slope consist of three types: ladder consequent bedding sliding, ladder consequent joint sliding, and wedge sliding.2. The principle of choosing mechanic parameters of rock mass in red bed is also put forward, we get integrated understanding on mechanic, hydrolytic and weathering characters of red beds via anlysis on test results and collected data in the first place. Then, the method using Hoek-Brown empirical strength criterion to decide mechanic parameters of jointed rock mass is expounded, the relationship between BQ and RMR is studied. From which empirical formula of using BQ to estimate elasticity modulus is summarized. Then, the principle of choosingmechanic parameters ot rock mass in red beds is proposed on formation structure and mechanic parameters in red bed slope. Mechanic parameters of rockmass with less than four groups joints is mainly obtained through test results of rock and structure planes. The test results have been processed with the random-fuzzy statistical method. Hoek-Brown empirical strength criterion is suggested to confirm mechanic parameters of rockmass with more than four groups joints.3. Studies are carried on stability of approximately horizontal slope. Numerical analysis has been done on complex interbedded strata of sandstone and mudstone slope to validate failure mechanism. Taking tensile strength as ripping falling criterion is suggested. Special study are carried on the horizontal impulse landslide with dense high angle joints on back of slope, the results show that the stability factor is minimal when the high angle joints with water are located in the top line of slope surface.4. Studies are carried on stability of dip slope. The author suggests using stereographic projection of structure planes to judge the failure modes of dip slope in red beds. Stereographic projection relationship of structure planes with two-faced slope is presented. The essential factors involved in stability of dip slope are presented as following: the formula from stress field used to calculate the bedding slip range of the consequent bedding rock slope with failure mode of sliding, the formula used to calculate critical slope angle, bending failure stress and breaking length of countertendency bedding rock slope, the formula used to calculate stability factor of wedge failure with different friction angles on two structure planes using limit equilibrium method and theory of plasticity upper limit method.5. The stabilities of red bed high slope excavated by step are studied. To cover the shortage of bench design based on experience, the influence on entire stability after setting bench and the width of wide bench in the middle of slope are studied. The results show slope stability after setting bench is slightly higher than that without bench. The excavation disturbed zone of slope is independent when the width of bench is wide enough. The K56 width of wide bench in Nanchong to Chongqing and highway is decided by numerical analysis.6. The methods to calculate internal force of lattice beam is presented. According to the difference of mechanical mode between rope-bolt and bolt, themethod calculating for single beam internal force, the mechanical model of lattice rope-bolt (bolt) frame design are put forward, whole winkle elastic foundation model for rope-bolt frame and for elastic bearing in node model for bolt frame. Examples on internal force of frame tallied with this theory is studied by FEM(fmite element method).7. The large-scale geomechanical model test is carried for discovering the mechanism and support measure. The results have testified that the failure mechanism of interbedded strata of sandstone and mudstone slope which is mainly caused by waters, setting the wide bench in the middle of slope is favorable to reducing the disturbed area due to excavation. The test results show the moment of resistance in lattice rope-bolt frame is consistent with theoretical calculation in the paper.更多还原