Mechanical Property And Simulation Experimental Research Of Dredging Grab

With the rapid development of global economy and international trade, totaltrade of China’s port rises steadily. The appearance of post-Panamax container shipsand large tankers prompts the ports to broaden and deepen waterways or constructnew terminals. Waterway departments must take considerable dredging tasks everyyear. On the other hand, the Hong Kong-Zhuhai-Macao Bridge and the Hong Kongairport reclamation works and so on also require a lot of seabed mining operations.Grab dredgers play a huge role in these projects. Mechanical characteristics of grabsin the sea or rivers affect not only the design and manufacture of grabs but also thequality and efficiency of the dredging projects.For underwater sediment environment of rivers and lakes, this subject analyzesthe theory of mechanical properties of grab dredging, statics and nonlinear finiteelement simulation, and experimental study of the grab mining process. And themechanical model of flat digging grab is proposed. The main research topics andresults are in the following areas:(1)Macroscopic theory and microscopic theory are studied on the basis ofkinematic analysis of dredging grab. The influence of different forces on excavationis also taken into consideration. The better resistance calculation method of grab ispresented as a result of comparison. Based on the existing theoretical models,mechanical model of flat dredging grab is built;(2)According to theoretical mechanical analysis of grab, finite element analysisof a typical dredging grab is taken. First, method of building a finite element modeland method of load calculation are given. Then, process of modeling is described indetail. As a result, stress and deformation of the grab under different operatingconditions are calculated. Based on the computation of modal data, the vibrationcharacteristics and maximum displacement is obtained;(3)Based on analysis of flexible multi-body system dynamics and physicalcharacteristics of soil, the impact of physical characteristics of soil and the pore waterpressure on soil is analyzed. Feasibility study that whether LS-DYNA can be used fordynamic dredging process is researched. Dredged soil is modeled in LS-DYNA. The process of flat dredging is simulated. And relationships between digging force anddifferent blade angle and different dredging depth are obtained;(4) Test of dredging process of a grab is taken on the basis of foregoing analysis.Forces of lifting rope and opening-closing rope are tested. Results of this test arecompared with theoretical calculations and numerical simulation in order to verify theaccuracy of the simulation results.