| Lock-up landslides are diverse and widely distributed.The key object of slope stability research is the locking section with energy-gathering effect.On the one hand,it can prevent the soil from sliding down and stabilize the slope;on the other hand,when it is damaged,it releases a lot of energy to cause more serious damage than ordinary landslides.However,there are currently many assumptions in the study of locking support theory,especially the locking effect of the “supporting arch” locking landslide and its impact on the stability of the slope are not clear.At the same time,less attention is paid to the evolution law of landslide surface cracks.Therefore,this article takes “supporting arch” lock-type landslides as the research object,and through physical model tests,studies the evolution of the surface cracks of such landslides,the “supporting arch” evolution law,and the influence of arch spacing on its locking effect;Based on the soil arch effect theory,a “supporting arch” force model was established and its locking effect was analyzed theoretically;FLAC3D was used to simulate conditions that were difficult to achieve in the physical model test,and the influencing factors of the “supporting arch” locking effect were analyzed.The main conclusions are as follows:(1)he physical model test further verified that the locking structure has a strong control effect on the stability of the slope.Compared with ordinary landslides without arch-supported locking structures,this type of landslides do not experience instantaneous large-scale collapse,which reduces the harm to a certain extent.(2)When the “span arch” height span ratio is between 0 and 0.32,the “supporting arch” locking effect is in the initial stage;if the high span ratio is between 0.32-0.47,the “supporting arch” is in the stronger locking effect stage;If the high-span ratio is between 0.47 and 0.54,the locking effect of the “support arch” is weakening;if the high-span ratio is greater than 0.54,the landslide has completely lost its locking effect.Based on this,it has certain guiding significance for the stability evaluation and treatment of "support arch" lock-type landslide in silt area.(3)The test group with an arch distance of 7cm is the optimal arch distance for this test.Compared with the test group with an arch distance of 9cm,the maximum sliding resistance is increased by 20%.When the landslide arch spacing is greater than the optimal arch spacing,the "supporting arch" locking effect becomes weaker,and the slope deformation is greater.When the arch spacing is less than the optimal arch spacing,the "supporting arch" locking effect is similar,but the slope damage is the most serious.On the basis of the test,the calculation formula of the optimal arch distance suitable for arch bearings is derived.(4)The evolution of cracks in the “support arch”-type locking landslides is regular,and their time and space locations are relatively fixed.In chronological orde:(1)trailing edge crack(2)feathery crack(3)lateral crack near the arch support landslide perimeter(5)arch support extends vertical crack(6)uphill arch pull crack.(5)When the sliding body speed is greater than 1mm/s,the arch support locking section will lose the locking effect.When the sliding body speed is less than 1mm/s,the effect on the locking effect is small.On the other hand,the "supporting arch" locking effect weakens with the increase of the offset distance of the arch support along the landslide sliding direction,and the soil flow shows a biasing effect,but compared with the sliding body without the arch support locking section,Yan still has a good anti-slip effect. |
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