答: (1)弹性平面问题的基本方程有:①平衡方程；②几何方程；③本构方程。(2)各方程的考虑方面①平衡方程从受力岩石平面中心力矩平衡，X轴向和Y轴向受力平衡考虑列出平衡方程组:[tex=9.786x5.786]GJYfMKjLkofbp2hHpywV2VrftS/hufKZXAkvTsx+hXHPmwaTrWAFdJU7bxW4+h9uKb8/KTz/xep6ZR8KQmpDV8bq+U8u11KlzV41cE7ov8jk3K240SeqhVU1wF2ubxEfkjNQkAL8cQbBx+lHEGvIjHME8N2OnZMtd/inIFx/p50D1TF0idgJ9YsdzMmz1vXTX3tpQwEqkkWt5mAAp10h2WVSmM+ri+bgHvCNkR9Qn2olPzfiJy1kELV862Hg+4ALY9yVkys0zSR+NLdMkaZIQXLzRUfJEb8B/zqt/9A4mZk=[/tex]②几何方程考虑物体受力后的形状和尺寸改变，推导应变分量与位移之间的关系，从而列出几何方程:[tex=14.929x2.643]MJiqW8ERWEWLjvX37Gs2VltqUnq3wuIA+bh1024qkg7umVY729feEIDv561OWcRKW9bbdNNnZBhv2cH3kKGKUpSGwGmdVoXzXHK9OizDKegDAfFTd5Q1J1nm+mNajNhbor1vnSH1IIad6JOCyqPOpfvCAu0aK6dYipTfScV68QbD9K7WZDaRCPnIUTjuQgHaNLUUPXk10c5UE49xPPyd/ZKBk1HcDZnuDRsLDTEoVyVBKtKubZ1EdPA+K2U9H/si[/tex]③本构关系考虑应力和应变的关系, 通过胡克定理建立本构关系方程组[tex=11.929x8.786]IfEG3NsBfGhtbCalasoF/9Ed+tjgHyCQxdGniU1tWXTlWUKw8vzoK9gYdZV+mQWAEOFxeIvYT9mddQVONQ1OwD/ypPYXfnRxN9tH7xYXBdDCeIeIkdOLRB5HQnv0EC4J/8s9wL9aO7cs/OBEP2rBiKUSeisorlM905nOsmsPhrfZ5vu9Fg0lPW2AdXmJJfbHd/OyidFZh8fQvITIe8KF58nUYAok9XFZDHDtK00syqqI+LXjlsFRDt4bOAmA3CZf0Yy5hHcNwT1U3zczETkJjFftH0FrSKSH1Xwa3mXXNqMQZ5vWAOG1MJoFX/m2UWVT[/tex]或[tex=8.571x7.643]thMFOI0/VnVsJT08kMg9k0pWb1QauJ1x4US9yeGygclUtx0LOewud1c29McexEcxWyYAlZEDEQeyJ5d2GCwA4r9+qyYfkQOUnqOxK9T5HxYAuZvFSwijcXRXNUZfGMasOuaJ49cN1eKJMPIep3Zb311mHZNsG9vlxnFMdaRhMcg/17BS+jHG757gdDQ5xq6U9rgsD/7h7oFoEjl+gCg1+xhu7twoT7+SXjU5gkOniNugyA0vd9T0r6xOQw57cBnkOGkX0Le/he0jNbEgSH7CvzAyXLq9+BMkyRV5NH3akW8=[/tex]