Study On The Application Of Shallow Dry Mixed Gravel And Grouting Pile-forming Method In Highway Maintenance

With the rapid development of Hebei's economy,the number of completed roads is increasing.Due to the complexity of road geological conditions,various roads will have various diseases,which have led to the rapid development of highway subgrade and foundation treatment technology.In order to better promote and apply shallow dry mixed gravel grouting piles to treat road settlement disease technology,it is necessary to carry out more in-depth analysis and research on the problems of single pile traits,composite foundation traits and control of road settlement.Based on the highway disease control project of Shixingjie to Shijiazhuang section of G308 line in Hebei Province,this paper systematically analyzes the highway engineering diseases by means of on-site investigation,drilling,geophysical exploration,field test and numerical simulation.The causes of this problem were analyzed and studied on the properties of shallow dry mixed gravel grouting piles,composite foundation properties and optimization of main design parameters,and the following results were obtained:(1)Through on-site investigation,exploration sampling and ground penetrating radar test results analysis,the asphalt pavement of Shixingjie to Shijiazhuang section(K639-K641)of G308 highway is affected by rain,overload and foundation properties,and cracks are generated on the pavement.These cracks are in the rainwater and Under the double action of the load,the crack gradually develops,causing the overall structure of the road surface to be destroyed,which causes some ruts and cracks on the road surface,which affects the road traffic safety.(2)Through the field test of the bearing capacity of the shallow dry mixed gravel grouting pile,the bearing capacity of the pile bearing capacity of the grouted pile and the un-grouted pile is increased from 70kN to 90kN,and the post-grouting pile The sidewall friction resistance is increased by about 28%.The numerical simulation analysis shows that when the load is small,the side friction resistance is not much,and the pile only affects the soil around the upper pile.With the increase of the load,the vertical displacement of the pile gradually increases.,and the sidefriction gradually develops.(3)According to the measured value and design value of the road surface deflection value,the reinforcement effect of the shallow dry mixed gravel grouting pile is simulated and analyzed.The settlement deformation characteristics under standard load and overload are studied.Among them:the road surface is subjected to normal load and overload 25 The deflection value after%is less than the design deflection value of 18.8mm,which satisfies the design requirements;after 50%overload,the road deflection value is greater than 18.8mm,which does not meet the requirements of design deflection value.(4)Based on the field situation,the influence of different pile lengths and pile spacing on the subgrade and pavement settlement of composite foundation was analyzed by numerical simulation method.Finally,the pile length of about 4.5m-6m and the pile spacing reinforcement of about 1.5m-2.5m were obtained.The effect is optimal.