# Analysis of Bridge Tests on Sandy Overburden Site with Fault Dislocating
###### Abstract
Hence, conducting proactive research on the damage mechanisms and seismic design of bridges near strong earthquake surface rupture zones, along with devising measures to enhance fracture resistance, holds significant practical importance and engineering application value. This will serve as a challenging yet pivotal aspect in the seismic design of bridge beams within intricate engineering geological conditions, particularly in regions prone to strong earthquake-induced fractures. Numerous scholars have conducted model tests to study the damage to bridge structures and their foundation soils in surface rupture zones due to bedrock fault dislocation. For instance, [PERSON], [PERSON] [20], and their colleagues conducted geomechanics similarity model tests on the Plateau bridge. They simulated the influence of site deformation near the fault on the failure of a simply supported beam bridge under horizontal load with a fault inclination of 70\({}^{\circ}\). [PERSON] [21], [PERSON] [22], [PERSON] [23], [PERSON] [24, 25], and others conducted shaking table modeling tests and numerical simulations to investigate the behavior of pile-soil-structures subjected to ground vibration. Their findings concluded that the sand soil layer amplifies the effect, while the clay layer induces a damping effect [26]. [PERSON] and [PERSON] [27] and colleagues conducted a shaking table array test on a bridge spanning a strike-slip fault, using the approach bridge of Pufan Bridge as a prototype with a 1:10 similarity ratio. The results demonstrated the effective protection of the main girder and bridge pier by lead-core rubber bearings and transverse blocking blocks. Additionally, the lead-core rubber bearings were found to protect the main girders and abutments, while the transverse block effectively restricted large deformations in the bearings. [PERSON] [28] conducted a seismic performance study on a steel-concrete composite rigid-frame bridge with double-layer steel-tube-concrete abutments (SCCRFB) under the influence of seismic surface rupture from a reverse strike fault. [PERSON] et al. [29], employing the linear static analysis method proposed by [PERSON] and [PERSON] [30], conducted a vibration test on a two-span concrete bridge with a 1:10 similarity ratio. Shaking table tests revealed that the fault rupture zone significantly influenced the location and type of damage to the foundation of the bridge row piers [31]. Physical modeling of bridges facing substantial bedrock dislocations is currently limited in both domestic and international contexts. While existing studies utilize shaker seismic simulation equipment, they struggle to accurately replicate the movement of underground faults and their impact on bridge structures, particularly through the rupture of foundation soil. Additionally, available loading equipment for simulating bedrock dislocation lacks the capacity needed to meet the size requirements of both the box device and the bridge model with overburdened site soil. The control of the loading process under bedrock dislocation poses a significant challenge. This paper addresses these limitations by introducing a self-developed \"bridge foundation-foundation-superstructure\" physical model for large-scale bedrock fault simulation testing. This model not only successfully simulates bedrock dislocation but also employs high-precision synchronous hydraulic loading. The research outcomes contribute to addressing the scarcity in the physical modeling of bridges affected by bedrock dislocations. Furthermore, the study explores the impact of bedrock dislocation on bridge engineering, considering the overburden. The findings enhance our understanding of the seismic mechanisms influencing bridge engineering under bedrock dislocations, the rupture-resistant capacity of bridges when facing overburden soil rupture and provide essential information for the standardized design and construction of bridge engineering sites near seismic fractures.