Study On The Deformation Characteristics Of Deep Marine Soft Soil Of Riverbank Extension Highway

The marine soft soil was widely distributed in China,it was a fine-grained soil containing organic matter and minerals with large natural void ratio,high compressibility,large perturbation,low shear strength,and poor permeability.Marine soft soil foundation treatment was an important part of foundation treatment,however,there were few studies about riverbank road required to be widened and the opposite riverbank required to be expanded and excavated which had a certain influence on the ground improvement of deep marine soft soil.Based on extension project of Yun Su road of Lianyungang,based on ABAQUS finite element software and established the model that accord with the actual situation of the project,studied respectively the reinforcement effect after the opposite riverbank was expanded and excavated,subgrade filling and before and after the opening to traffic.Finally,the numerical simulation results,the theoretical results and the field measurements were compared and analyzed,and research results indicate that:(1)For deep marine soil,through comparing and analyzing engineering applicability and engineering economics,selecting Bidirectional Dry Jet Mixing(BDJM)pile and plastic drainage plate to improve deep marine soil(2D method);there is an oblique intersection of deep marine clay with weathered rock layer and road near the river intersects with the mountain,the use of Concrete Prefabricated Square Pile can meet the needs of engineering;(2)based on ABAQUS finite element software,the opposite riverbank is expanded and excavated will have a certain influence on ground improvemrnt in two range.Along the depth of the foundation,the right edge of the subgrade is shifted to the riverbank,and has less influence on the left edge of the subgrade.Relevant measures need to be taken to protect the subgrade slope;(3)based on ABAQUS finite element software,subgrade filling and before and after the opening to traffic will have a certain influence on the ground improvemrnt in two range.Along the depth of the foundation,the lateral deformation of the foundation at the left and right edges of the subgrade continue to increase,and the settlement on the surface of the foundation also continue to increase.The curve shows "three regions and two transitions",however,the increase of lateral deformation and ground surface settlement is becoming smaller and smaller,which indicates that the protective measures of subgrade slope and the effect of pile foundation retaining wall are significant;(4)The following conclusions can be obtained by comparing the field measurements,the function prediction results,the theoretical results and the numerical simulation results: For deep marine soil,2D method and Concrete Prefabricated Square pile can meet the requirements for design and post construction settlement and stability.The hyperbolic method can reasonably predict the final settlement value of the deep horizontal displacement observation points which tend to be stable;The results of numerical simulation of composite modulus method and pile-soil separation are different from the measured values.