黄泛区粉土路基冲击压实动力特性研究与机理分析

发布时间：2018-03-22 01:30

本文选题：冲击碾压　切入点：粉土路基　出处：《山东大学》2016年硕士论文　论文类型：学位论文

【摘要】：路基是道路的重要组成要素之一,承受由路面传递下来的荷载,路基的均匀与稳定直接影响道路的使用性能,有效的压实能明显提高路基的强度与稳定性。目前,路基压实常采用振动压实或静力压实,该种压实方法具有压实度较均匀、压实质量易控制的优点,但其压实能量较小,允许的铺层厚度较薄,且施工效率慢,对建设工期短的工程不适用。对于黄泛区土质而言,其组成以粉土、粉质粘土为主,孔隙比大,含水率高,压缩性大,如何快速有效地进行压实是一个重点和难点问题。与传统压实机械相比,冲击式压路机由于其压实能量大、施工速度快、压实效率高、费用低、允许的含水率范围较大,同时对压实层以下的土体仍有补强作用,故而越来越多地应用在道路工程中。由于冲击碾压技术起步较晚,尤其在黄泛区路基施工中的应用较少,施工工艺参数、动应力传播规律与加固机理等尚不明确,严重影响了该技术的深入研究与发展。依托正在施工的济南-东营高速公路,通过室内土工试验、现场试验、数值模拟等手段,对黄泛区路基填料的土质特性、粉土路基冲击压实的效果、动应力分布规律及其作用机理进行了分析,推荐了适用于黄泛区路基分层冲击压实的工艺参数,主要研究结论如下：(1)通过对比分析4种不同松铺厚度粉土路基的冲击压实效果,得出粉土冲击压实使用用于路堤区,而不适用于路床区,且适用的含水率范围可适当放宽。针对不同的松铺厚度,可取最后5遍碾压后压实度增量小于1%所对应的碾压遍数作为有效压实遍数。(2)根据经济有效原则,推荐黄泛区粉土路基冲击压实工艺参数：对于YCT-25型冲击压路机,最佳松铺厚度为0.8m,允许的含水率范围可扩大至ωop-5%≤ω≤ωop+4%,最佳碾压速度为10-12km/h,最适宜碾压遍数为20遍。(3)冲击荷载具有瞬时性,连续两次冲击作用产生的动应力无明显叠加现象,动应力峰值沿深度方向具有滞后性；松铺路基冲击压实过程中路基内部某一深度位置处的动应力峰值随冲碾遍数的增加呈先增大后减小的规律；冲击点两侧各深度位置处的动应力沿纵向近似呈对称性,冲击点前的动应力大于冲击点后的动应力；土体内部竖向动应力、侧向动应力和竖向位移沿深度方向呈现类似的变化规律,且均出现明显拐点,同一变量的拐点基本一致,并据此提出了土体冲击压实内部动应力分布的简化模型；对于YCT-25型冲击压路机,理论影响深度约为3.7m,径向有效影响范围约为lm。(4)粉土的冲击压实过程在宏观上大致可分为4个阶段,即松散土体阶段(吸收能量)→土体密实阶段(传递能量)→板块形成阶段(扩散能量)→板块下移阶段(松动区增厚)；在微观上可大致分为三个阶段,即动载输入、振动传播和介质运动。该研究成果的取得,可为路基冲击碾压相关标准、规范的建立提供实际工程资料,为黄泛区粉性土路基冲击碾压施工工艺参数的选取提供依据,有助于冲击碾压技术的理论研究与发展,具有显著的工程意义和社会经济效益,前景十分广阔。
[Abstract]:Subgrade is an important element of the road, the load passed down from the pavement, subgrade uniformity and stability of a direct impact on the use of the road performance, effective compaction can improve the strength and stability of subgrade. The subgrade compaction often uses static compaction or vibration compaction, the compaction method has advantages of compactness is uniform. Easy to control the quality of compaction, but the compaction energy is smaller, allowing the layer thickness is thin, and the construction efficiency is slow, not suitable for short period of construction project. For soil Huangfanqu, which composed of silt, silty clay, large void ratio, high water content, large compressibility. How to effectively compaction is a key and difficult problem. Compared with the traditional mechanical compaction, impact roller compaction due to its high energy, fast construction speed, low cost, high efficiency of compaction, the moisture content of a large range of allowed, At the same time there are still a reinforcing effect on soil compaction layer below, it is more and more used in road engineering. Due to the impact compaction technology started late, especially seldom used in subgrade construction in flood area, construction parameters, dynamic stress propagation and reinforcement mechanism is not clear, serious impact on the further study with the development of technology. Based on the ongoing construction of the Ji'nan Dongying expressway, through laboratory soil test, field test, numerical simulation, the characteristics of the soil subgrade filling of the flood area, silt subgrade impact compaction effect, dynamic stress distribution and its mechanism are analyzed, the recommended process parameters for in the layered Subgrade Huangfanqu impact compaction, the main conclusions are as follows: (1) through the comparative analysis of 4 different paving thickness of silt subgrade impact compaction effect, the silt impact compaction for use The embankment area, and is not suitable for roadbed, and suitable water content range can be relaxed. According to the different thickness of the last 5 times, desirable compaction after rolling increments less than 1% corresponding to the rolling times as effective compaction time. (2) according to the principle of economic efficiency, recommend the silt subgrade of Yellow River shock compaction parameters: for YCT-25 type impact roller, the best paving thickness is 0.8m, allowing the moisture content range can be extended to op-5% = Omega omega = Omega op+4%, optimal rolling speed is 10-12km/h, the most suitable rolling times for 20 times. (3) the impact load with instantaneous, continuous two times the impact of dynamic stress was not overlapped, the peak value of the dynamic stress along the depth direction has a lag; loose pavement impact compaction process of subgrade subgrade within a certain depth at the position of the dynamic stress was increased first and then decreased with the increase of the peak force of impact rolling times; impact Click on both sides of the depth position of dynamic stress along the longitudinal direction is approximately symmetrical, the impact point before the dynamic stress is larger than the impact point of the dynamic stress; soil vertical dynamic stress, lateral stress and vertical displacement along the depth direction showed a similar variation, and there were obvious turning point. The inflection point of the same variable are basically the same, and puts forward the soil compaction dynamic simplified model of internal force distribution; for YCT-25 type of impact roller, the theory of influence depth is about 3.7m, the radial effective range is about lm. (4) impact compaction process of silt in the macro can be divided into 4 a stage, namely loose soil stage (energy absorption), soil compaction stage (energy transfer), plate formation stage (diffusion energy), plate down stage (loosening area thickness); at the micro level can be roughly divided into three stages, namely the input dynamic load, vibration propagation and transport medium The research results obtained., for the impact compaction of Subgrade of the relevant standards, norms established to provide practical engineering data, provide the basis for the selection of Yellow River silt impact compaction of subgrade construction process parameters, theoretical research and contribute to the development of impact rolling technology, has significant engineering significance and social and economic benefit. The prospect is very broad.

【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U416.1

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