Study On Key Techniques Of Sinking And Discharging On Ice In Nenjiang River(Qiqihar Section)

1.Sinking on ice is a common ice construction technology in winter in northern China.It is mainly used in bank protection projects.In different areas,suitable types of drainage and construction techniques should be selected according to the form of bank slope failure and mechanical properties of ice.The embankment of the main stream of the Nenjiang River in Heilongjiang Province is 650.439 km long.Most of the embankments are raised on the foundation of the embankments.However,due to poor soil quality and serious river erosion,measures must be taken to protect the embankments.The Nenjiang River is long and cold in winter,and the construction period of water conservancy projects is short.The ice-drainage and drainage technology can effectively solve the problems that cannot be solved by some conventional protection methods.This study aimed at the bank protection project for the main stream of the Nenjiang River(Qiqihar section),and explored the key technologies for ice sinking and drainage in the area from the aspects of ice bearing capacity,sedimentation and drainage materials,construction period and precautions,etc,hoping to provide revetment for the future cold area.Project construction and safety operations provide a reference.2.In this study,a prototype test was conducted in the Nenjiang River(Qiqihar section)during the winter of 2016-2017.The temperature and ice thickness changes were observed.Nine groups of in-situ cantilever tests were conducted.The results showed that the minimum temperature in the area appeared in January.From early January to early February,the maximum ice thickness appeared from late January to mid-February,the minimum daily temperature was-20°C,and the maximum ice thickness was 94 cm;the in-water cantilever pull-up test flexural strength of the river ice was between 441.8 and 553.0 kPa.The average flexural strength is 497.4 kPa;the flexural strength of river ice in situ cantilever under test is between 206.9 and 696.4 kPa,the average flexural strength is 495.1 kPa,the elastic modulus is between 3.79 and 7.18 GPa,and the average elastic modulus is5.10.There is no significant difference in the mean value of the river ice bending strength obtained by GPa,in-situ cantilever pull-up and pull-down.3.The construction of the ice sink and row is mainly based on the bearing capacity of the ice layer.According to the prototype test,the relationship between ice thickness and bearing capacity is determined by empirical formulas and measured formulas.It can be seen that when the ice thickness reaches 50 cm,the ice capacity can reach 8.75.~17.5 t/m~2,the measured ice bearing capacity is 7.16 t/m~2,and the ice bearing capacity of Nenjiang(Qiqihar section)is less than the empirical value.It is known from experience that ice sinking and rowing construction is required after the ice thickness reaches 50 cm,while the main stream of the Nenjiang River is recommended for construction after the ice thickness reaches 56 cm.There is no significant fluctuation in climate in Qiqihaer for many years,and there is no major change in the freezing period year by year.This study shows the relationship between winter ice sheet bearing capacity and ice thickness in the area.It is suggested that ice sinking and drainage be carried out from early January to mid-February.The ice bearing capacity can be effectively utilized.4.The model test can provide help for prototype testing to a certain extent.In this study,a static ice indoor cantilever test and a simulation sink test were performed according to the prototype test.The results show that:the internal cantilever under test has a bending strength of 417 kPa~1197 kPa.The average bending strength is 842.5 kPa,which is greater than the field value,mainly because the indoor ice crystal structure is columnar ice,while the field ice structure is columnar ice and granular ice;manual grooving can be reduced during the construction process The time required for the sinking of the small sink row;indoor ice sinking and rowing model test can break the seasonal limit,and explore the construction of the sinking and draining in a certain degree under better experimental conditions,but there are still a lot of deficiencies that need to be on the ice in the future.Deposition model test for further study.5.Through the consolidation and analysis of historical data on the subsurface sedimentation of the Nenjiang River(Qiqihar Section),as well as on-site observations and field investigations,it is recommended that the construction of the gabion be used for the construction.This study puts forward detailed suggestions on the design,construction process,construction process and construction quality control of the sinking and drainage in the process of construction of the gabions,and hopes to provide a certain technical reference for the bank protection project of the Nenjiang River(Qiqihar section).This paper aims at the problem of construction and settlement of ice on the ice in Nenjiang(Qiqihar section).Through prototype tests,model tests and field investigations,etc.,the ice bearing capacity,effective construction period,the feasibility of indoor subsidence and drainage simulation,and the selection of suitable types of subsidence and drainage are discussed.It is a key technology that needs to be determined in the construction of ice sinks.