Numerical Analysis And Quality Control Of Dynamic Consolidation Of Silty Soil Subgrade In Yellow River Alluvial Plain

The silty soil in Yellow River alluvial plain is the unique soil quality in our country.The soil has high abrasive roundness,and the particle size is relatively single.The particles are difficult to embed effectively,and the quality of compaction is not easy to control.On the other hand,the construction depth of the conventional roller compaction of highway subgrade is relatively shallow.After the compaction of such soil,the surface is easy to loose,and the work efficiency is low,and the subgrade construction often accounts for more than half of the total construction period.Therefore,a fast reinforcement technique of silt subgrade in Yellow River flood area needs to be formed and perfected.As a mature foundation strengthening technology,dynamic compaction has such advantages as simple process,low cost,large depth of reinforcement,fast construction speed and so on.It has been popularized rapidly after being introduced into china.With the development of dynamic compaction technology,the technology has been gradually tried to use in highway subgrade filling project,but it has not been widely promoted.First of all,the reinforcement of highway subgrade engineering has no mature experience for reference,the relevant parameters in field compaction test to determine the complicated process and the need to spend a lot of manpower and resources;secondly,reinforcement of foundation and subgrade reinforcement effect evaluation emphasis is not exactly the same,but the current standard is not on the subgrade dynamic consolidation effect evaluation and control;moreover,after compaction subgrade in space is not uniform,the current specification has not on the subgrade uniformity evaluation including subgrade stiffness uniformity and settlement uniformity evaluation.It can be seen that both at home and abroad have not formed a set of effective evaluation of subgrade compaction standard and method of strengthening quality and uniformity of subgrade is the key question of this series has restricted the popularization and application of dynamic compaction in highway subgrade in engineering.Based on the above problems,the feasibility on the basis of the field test system on subgrade compaction of numerical simulation,and the silt subgrade Yellow River alluvial plain compaction Technology launched a detailed study by numerical simulation,including best single tamping,tamping,tamping point check to determine the standard distance of dynamic compaction the parameters of compacted subgrade reinforcement effect evaluation and uniformity evaluation index and standard etc..The research results of this paper solve the key technical problems which restrict the dynamic consolidation of dynamic consolidation on subgrade,and have important social and economic significance.In general,the main conclusions are as follows:(1)Dynamic change can be achieved in the process of soil compaction modulus,cohesion,friction angle,yield stress and mechanical parameters of user subroutines for numerical simulation of dynamic compaction,can be more accurate and reliable simulation of compaction process,the result is reliable;(2)The method of determining the compaction compaction energy and the standard of tamping and compaction for the dynamic consolidation of subgrade with different heights is put forward;(3)The analysis method for evaluating homogeneity of compacted embankment,put forward to the road surface compaction between rebound at sink<l + 2S and the road surface compaction compaction the rebound deflection is less than the road surface roughness as the stiffness evaluation of the uniformity of the embankment standard,with gradient<0.4%uneven settlement of embankment as uniformity evaluation the settlement of embankment standard;(4)The dynamic consolidation technology of different subgrade height(4m,6m)was studied,and the corresponding dynamic consolidation parameters were put forward.The research results of this paper have important reference and guidance significance to the subgrade dynamic consolidation engineering,and the social and economic benefits are remarkable.