静钻根植竹节桩纵向振动特性及应用研究

Vertical vibration characteristics of static drill rooted nodular pile and its applications

针对"静钻根植竹节桩"这一新桩型的特点,建立考虑桩周土径向和竖向非均质的桩体纵向振动定解问题.采用阻抗函数递推方法,结合拉氏变换对定解问题进行求解,得到桩顶阻抗函数.利用卷积定理和傅里叶逆变换,求得任意激振力作用下桩顶速度响应的半解析解.通过比较低频范围内桩顶复刚度响应曲线和时域内桩顶速度响应曲线,分析竹节长度和竹节半径、桩周扩底高度和扩底半径、浆液配比及桩周水泥土硬化的时效性和搅拌均匀性等因素对桩顶动力响应的影响,揭示这一新桩型的动力特性.将理论计算曲线与现场实测曲线进行拟合对比.结果表明:理论计算曲线与现场实测曲线较为吻合,采用所建立的模型能够较好地反映静钻根植竹节桩的实际动力特性.

Aiming at the characteristics of a new kind of pile named static drill rooted nodular pile,the vibration problem of pile considering the non-homogeneity of soil around the pile in both radial and vertical directions was inrestigated.The impedance functions of a pile about velocity and displacement were derived by means of impedance recursive method integrated with Laplace transform.Then,the semi-analytical solution for the velocity response of the pile subjected to a semi-sine wave exciting force was developed with convolution theorem and inverse Fourier transform.Through comparison of the response curve in low frequency domain and the response curve in time domain,the effects of several factors were analyzed,such as：the length and radius of bamboo joint,the height and radius of expanded-base,the ratio of cement in the serum,the timeliness of the hardening of cement-treated soil around pile and the mixing uniformity.Thus,the dynamic response of the pile was revealed.Finally,the theoretical calculation curve was compared with the directly measured curve by fitting.Results show that the proposed model can primly reflect the real dynamic characteristics of static drill rooted nodular pile.